I am a big fan of Gale Force Nine's (GF9) products. GF9 now produces some official game accessories for 4e, including the DM's Token Set (my review can be found here), maps and character token sets by class. GF9 had a prerelease of the Player's Handbook character tokens at GenCon. The Hopeless Gamer picked up the fighter set at GenCon and those tokens saw use during our last session (in the Tomb of Horrors no less, check back in the next two weeks or so for more on that campaign).
The Fighter set seemed pretty useful with tokens for marking among other useful items. If you are not familiar with the 4e fighter, the fighter marks any enemy he attacks, forcing the enemy to attack the fighter on its turn or take a minus 2 penalty to its roll. Since some fighter attacks target multiple enemies, it is nice to have a few extra tokens to cover all marked enemies.
The sets also come with a small, dry erase tracker for conditions, surges, hit points and temporary hit points. The Hopeless Gamer used it in our last game and commented that it was much easier and less cluttered to follow than the normal character sheet. Anything that speeds up play is a bonus in my book. Each set also comes with a horse mount (with a different color for each set) and a translucent character standee. The standee is ok as a mini for a player character, but will really shine for a board representation of a player in stealth.
GF9 also showed off some of their maps for 4e, including a Con exclusive map. The maps, of course, can be used for any fantasy rpg out there. They look pretty nice, but I decided to hold off on picking up any of the maps for a later date. I am not usually a fan of Con exclusives and I hope that GF9 has these maps available at some point in the future for those unable to attend GenCon.
Wizards of the Coast had a fun, quick event available at their booth this year. Essentially, a group of six players each picked a very simplified 4e character to play in a two round combat against either a white dragon or a wraith. The large cardboard stuandups and dungeon tiles were a fun way of bringing 4e to life. I played as a Minataur Battlemind and received a large, laminated character card with my player info on it to wear around my neck. My sister took the Eladrin Ranger (I believe).
Most of the players rolled a high enough initiative to act before the dragon. The two defenders and a striker immediately closed with the dragon and two of us, including myself, managed to deal some serious damage. The dragon would later hit some of us for decent damage with its claws. Two of the three remaining players hit for more damage. During the second round, I hit along with one of the other players in melee before the dragon killed me with its breath weapon. My sister was the last player to act in the second round and the dragon was still breathing. She rolled the giant die along the dungeon tiles and rolled a 20, killing the dragon with her critical hit!
As a reward, we each grabbed a random token out of the treasue box. Both my sister and I both grabbed red gems (apparently one of the most valuable in the box) and went up to the second floor of the convention center. Once we were in the RPGA room, we turned our gems in for Promo cards for the upcoming Castle Ravenloft boardgame, plus we were able kept our large character cards. All in all, the experience was very fun, especially since we randomly stumbled upon the event right before the hall closed.