Clothing:
Size 4T and up

Toys:
Age 4+ is probably a safe boundary. Quiet and/or constructing/creating (Lego, K'Nex, etc.) toys preferred.

Books:
Any Owly books other than "Tiny Tales" and "Flying Lessons" - he already has those.
Other age-appropriate books

Art supplies! (Washable paint, colorful paper, etc. - but note he has a lot of Play-Doh already)

Wishlist

Books:

Little Brother, Cory Doctorow
Any of the Vorkosigan Saga books by Lois McMaster Bujold, except Cordelia's Honor/Shards of Honor/Barrayar (note - a lot of them are in omnibus editions now under different titles than the individual books)
The Curse of Chalion, Lois McMaster Bujold
Battle Royale, Koushun Takami (2009 reprint/retranslation)
Dunegons and Desktops, Matt Barton (non-fiction)
How NOT to Write a Novel, Howard Mittelmark and Sandra Newman (non-fiction)

Alternately, you can look up my wishlist on Powell's - there's some overlap between here and there but it's all valid. (The email address is our family address.)

Gift cards (Barnes & Noble, Powell's, et cetera)

Manga:

To Terra, Keiko Takemiya
Fushigi Yuugi Genbu Kaiden, Yuu Watase (vol. 7+)   (Note: Not to be confused with the original Fushigi Yuugi)

Games: (Note: used is fine, some of these may hard or impossible to find new)
Apollo Justice: Ace Attorney (Nintendo DS)
Star Ocean: Second Evolution (Sony PSP)
Dragon Quest V: Hand of the Heavenly Bride (Nintendo DS)
Avalon Code (Nintendo DS)

Music:
CDs:
Steely Dan
*Katy Lied
*Countdown to Ecstasy
*The Royal Scam
*Gaucho

Heart
*Dreamboat Annie

Hall & Oates
*Bigger than the Both of Us

Gino Vannelli
*Nightwalker/Black Cars (two-album remaster - the original, individual CDs are out-of-print and hard to find, alas)

Amazon.com gift cards (for the MP3 store)

DVD:
Anime:
Romeo x Juliet: The Juliet Collection (episodes 13-24)
Legend of the Seeker (TV series)

Blu-Ray:
Sleeping Beauty

Wishlist:
Wacom Cintiq
The Nightfly Trilogy (Donald Fagen)(7-disc set)

Books:
Schlock Mercenary: The Blackness Between
Schlock Mercenary: The Teraport Wars (www.schlockmercenary.com)

Manga:
Midori no Hibi, Kazurou Inoue

Games:
Overlord II (PS3)

Board Games:
Munchkin Quest (based on the card game "Munchkin" - Steve Jackson Games)
Battlefleet Gothic minis! (Chaos Fleet preferred)

Music:
Bargainville, Moxy Fruvous
Albums by Jonathan Coulton (may be hard to find, some are out of print)

Amazon.com gift cards

Blu-Ray:
Batman Begins
The Dark Knight
Star Trek

DVD:
TV:
Babylon 5, all 5 seasons
Chuck (Season 2)
Good Eats DVD sets (any)
Gargoyles (animated early-mid-90s TV series)

Other
Adventure Gaming Dice Sets
Zero Punctuation Imp Plushy

Honing steel

Wishlist:
Cheap, extremely fuel-efficient car (Geo metro, etc)
Bleeding edge desktop computer

Blu-Ray
Meet the Robinsons
Up

DVDs
A Prairie Home Companion
The Middle Man (TV series)

Wishlist:
Monty Python's Flying Circus Complete Series