Does your tabletop gamer already have all the games you can think of? Don't want to buy a game they might not like? How about upgrading their game instead?
Plenty of games come with the minimum necessary number of dice to keep the game... er... rolling. A lot of time can be wasted just looking for the one D8 that came in Battlestar Galactica. Sometimes it's just another D6 that can really help out. The dice above are from Super Dungeon Explore and, fortunately, CoolMiniorNot offers a pack full to reduce time searching for them. Fantasy Flight Games offers packs like this for Star Wars: X-wing and Descent as well. Dice sets usually run $10-15 for most custom dice sets and many can be found at sites like Cool Stuff Inc. or a nearby game store if you prefer local.
Sleeves. Some games get played. Great games get played a lot. A board game will start to show its wear over time, but an excellent way to keep them from aging so quickly is to sleeve the cards that come in the set. Not sure what size to get? Fantasy Flight marks the back of their boxes so you know exactly what size and how many you need! Just check the back of the box the next time you play. Say you're looking for instructions or something. In addition to protecting those cards, they can be used to add a little flair to the game by introducing art sleeves, like the ones above. A load of different card sleeves can be picked up at Cool Stuff Inc for $1-5 a pack based on quality and art.
Upgrade the tokens! Several card games have lousy cardboard tokens. Depending on the quality, they could bend and tear with little effort. For those games, I bring you the Fantasy Flight game tokens. They come in several different colors, allowing you to grab red for wounds, gold or silver for money, and many other uses based on color.
First player markers. Some games have that wimpy token that looks like it was just there to fill out the cardboard sheet. Some games, like Twilight Imperium, just need a player marker in the first place. It's such a good idea that Gale Force Nine encouraged players to get a dinosaur as a marker for their Firefly game and asked players to take a picture. They handed out a special promotional card to those that did.
Battlefoam creates trays for several games already. Privateer Press, Wyrd, and Cool Mini or Not are just a few companies that have contracted custom trays with Battlefoam. If you don't think one will fit your gamers needs, you can use the Custom Tray Creator to make your own. Get a few dimensions for card decks, tokens, and game boards and make it the right size for the box and you'll have a very happy gamer.
Give them something to carry it in. The above messenger bag is one specifically made by Battle Foam for the Iron Kingdoms RPG. Any Messenger bag would help out an RPG gamer. Several bookbags are big enough to hold RPG books or a board game or two.
Tackle Boxes like this one aren't just for fishing. Gamers have adopted them for their own uses. Some players go so far as to toss the original box and put it all in one of these. Games like War of the Ring and Descent usually won't fit in their original box once all the expansions are thrown in.
Add a personal touch. Probably one of the best gifts I've ever gotten was from a friend that painted my vipers for my frequently used copy of Battlestar Galactica. They normally come in a plain plastic gray color. If you don't have much money to spend, but a little skill instead, painting minis for a board game really can make the game stand out.