I enjoy reading the "What's in your bag?" thread.  It gives me good ideas for what to bring.  I've since adjusted what I carry with me during Gen Con.  I've both added and taken away items.

I think it'd be interesting to have a thread on what you have brought in the past, but found unnecessary and hence don't bother bringing any more.  While some here are "vets" and have it dialed in, I think this would help the newer attendees have a better idea for what should be left behind.

I'll start.

Rulebooks for my RPG's events:  They were heavy (after carrying them the full day), and at the gaming table were rarely needed.  Additionally, there are always people around who have them, especially the GM.  Speaking of which...as a GM, try to only bring the necessary core book(s).  If you can have the books electronically, then fine.  Otherwise, I'd say try to make due without them.

Drinks/snacks like I was going to be out for 2-3 days:  I wanted to make sure my daughter & I had enough to get us through the day.  I always returned to the hotel with a few crushed granola bars and unopened bottles.  Now, I bring one bar and piece of fruit for each of us and we carry one water bottle to refill at the con.  There are plenty of places to eat and drink around the area, and I'd say it's a good idea to schedule a meal break during your day anyway.

Swag:  I loved picking up swag, both from the goodie bag back in the day and from various vendors.  It was exciting to get my hands on new/limited items/promos.  However, I've learned that once I got back from the con and the dust settled, the random swag was not all that great.  Promos for games you don't play and are not really interested in is just a waste of space.  Don't bother with swag you don't really care about.  Perhaps there's the aftermarket aspect, but cards for some obscure game that will fetch $1 on ebay are not really worth your precious Gen Con time/effort.

So, what item(s) have your carried before that you no longer bring or bother with?
 

My purse, in the past I have brought my purse and all of its contents. I now have a small backpack and I'm only putting in it what I feel I need to bring. 

I may leave the credit cards at home too and only bring cash. We've had issues with the bank before since there are vendors from so many different places (always let your bank know you will be traveling!). I'm also afraid of accidentally leaving it somewhere, accidentally leaving a few bucks isn't quite as bad as giving someone access to my bank/credit account.

Just remember to not skim yourself down too much! You never know what is going to happen while you're away from home and should be prepared for unexpected. Be sure to bring your health insurance card, ID, extra medical supplies you may need (for me that's an extra small bottle of contact solution and a case), etc..

In my "murse"/man purse I don't carry anything that can't be replaced. My magical dice (yes, they're magical), custom painted miniatures and jewelry and watches can all stay at home. I once lost a ring at a convention because it fell off while I was helping break down the gaming area.

Mike B is not in my bag this year.

My tablet.  I always *think* I'll want it, and I never wind up ever turning it on.

Once back at the hotel, I use it quite a bit, but at the con, it never leaves the bag so this year, it's staying in the luggage.

Another vote for not carrying rulebooks - If you don't (absolutely) have to have them, leave them at home.  Your back will thank you.

Tablet - Unless there's (absolutely) a need for it, leave it in your hotel room.

Any game bigger than a deck of cards/tube of dice.  If you're on your way to play it with someone, great.  Otherwise you probably won't have time to set up (not to mention a place to do so unless you've planned it that way).

Being able to drop off purchases is a great incentive for not packing crap around all day.  If your hotel isn't connected getting back to your car to drop purchases or waiting until  you can make a consolidated trip to make those purchases takes some practice/coordination with your group.

Random magic decks or card games, i used to keep a 'filler' game in my bag and realized over 3 cons it never got pulled out. Snack i keep a breakfast bar or 2 and that's it. Rather keep hydrated and settle for real meal break later. 

For TD it's pruning down extra tokens, keeping my builds and that's it. If i need to swap stuff around or deal with trade goods it'll wait till i get back to hotel room and rest of my binders/tackleboxes.

I don't bring my wallet. I carry my ID, debit card, and cash in my badge. I use a Gen Con badge holder. I don't worry about it being stolen (not that this is a problem) and I always have it around my neck. 
 

Chocolate! 

Bringing a snack is great.  But, it gets a bit warm inside, and a lot warm outside.  Chocolate will turn into a disgusting mess that you will never actually eat (or will regret eating if you try and eat).

Rulebooks.  I do have an app on my phone with the Pathfinder rules, and there's probably comparable apps for a lot of other games. Or get a PDF if you really feel the need to have a rulebook.  Unless you're GM'ing or playing a really rules-heavy game, you probably won't need anything at all.

Tablet.  I used to use one for the rulebooks, and it was an improvement over paper, but now that I have a smartphone the tablet is just ballast.

The program book.  The main thing I used it for during the day was the maps, and now they're on the Unofficial Gen Con App. I do pick up a copy of the program book, and I read bits of it on Wednesday night, but it doesn't stay in my pack.

Might not be a popular opinion, but I've found bringing a sandwich or other more "substantial" food to be a total waste. I usually have a container for Goldfish or something similar if I want something light, but when I want a proper lunch or other meal, I usually want something more than just a PB&J and end up at the food trucks. I always brought a sandwich just to toss the now very squished and sad sandwich at the end of each day.

This. Tried saying I'd be frugal, make sandwiches and eat cheap. Ended up throwing said sandwich away along with the dirty plates from the food truck.

Cliff bar is the most food I bring.

I used to carry a poster tube with me in case I bought posters and wanted to keep them safe...not, like, inherently a terrible idea, but so situational and so bulky that I dropped that after two years.

I also used to bring a dedicated digital camera, and that was always too much bulk, but, well, that is not a problem many people still have :)

The last thing that comes to mind is "a folder stuffed with funny memorabilia from previous conventions," or basically anything that you know full well serves no purpose.  Look, comedy is a wonderful thing, but there will be plenty of amusing things to find THIS YEAR, you do not have to call back to previous years.  Look I know I am not the only person who does this, I know a guy who probably has a half-dozen accessories he only wears when at Gen-Con, and he adds more every year or two, and has to carry them all day.  Just saying!

Great thread topic by the way.

I'm not bringing my pistol! No way no how. No matter how much it bugs me!

I no longer bring large numbers of dice.  A couple sets is plenty.  If you need more, you have a table full of new friends to loan you some.

My first nascrag was played when I had not bought any dice at all :D

Do not carry books, do not carry my tablet. Do carry dice, water bottle and energy bar, note book, pens, oh, and a small flashlight.