Comic Touch from Plasq. Although the iPhone's camera is absent, the ability to edit, annotate and humorize synchronized photos on the touch is a delight. Comic Touch may not be the only app in this space but it's proven its worth to me during evenings out or when traveling, as my daughters derive endless fun from captioning family snapshots with thought balloons.
Pandora Radio. Making the portable device into a full-featured internet streaming tool is a work in progress, but a WiFi-connected iPod touch with Pandora is an astonishingly fun and surprising music source, a glass-front Airport Express. I love the Pandora web app, so I was prepared to like the miniaturized version -- what I didn't expect was how connecting it to a stereo and letting it play would lead to "Wow, who's this?" moments. Lacking a microphone, I can't run Midori or Shazam on my touch -- but I can make iPhone users want to use those apps to find out what Pandora is playing through my speakers.
Scrabble. Yes, I know that Facebook users have dartboards covered with pictures of Hasbro's legal team -- I still enjoy the EA version immensely. It's colorful, easy to play and has the feel of the tabletop game and the tactile letter-dragging fun you expect. Shaking the device to shuffle the rack aside (it feels gimmicky and I never do it), all I really want to add is a copy of the Scrabble dictionary for training and reference.
Location-aware touch. Even without the GPS of the iPhone, I've been pleased that so many location-aware apps work just fine on the touch. Where To?, Twitterrific, Urbanspoon and Now Playing -- assuming there's a WiFi network around -- behave just as they would on the iPhone, and whether it's due to the solid location frameworks or thoughtful work by developers, I'm appreciative.
Honorable Mention: Simplify Media, Dot Game, City Transit NYC, and Facebook.