Google sample creative for publishers, a work in progress started Thanksgiving weekend 2005 during a lull.

Google's new publisher referral program has ads like these:

Samples of Google AdSense ads in varuous formats

Leaderboard (728 x 90)

Banner (468 x 60)

Button (125x125)

Half Banner (234x60)

Skyscraper (120x600)

Wide Skyscraper (160x600)

Small Rectangle (180x150)

Vertical Banner (120 x 240)

Medium Rectangle (300 x 250)

Square (250 x 250)

Large Rectangle (336x280)

Link Units

(120x90)

(120x90_4)

(160x90)

(160x90_4)

(180x90)

(180x90_4)

(200x90)

(200x90_4)

New! (468x15) Displays up to 5 links
468x15

New! (468x15_4) Displays up to 4 links
468x15

New! (728x15) Displays up to 5 links
728x15

New! (728x15_4) Displays up to 4 links
728x15