There are quite a few great birthday stamp sets in the front of the Occasions catalog and some great designer series paper options as well.
I have used some Party Animal designer series paper and the Super Duper stamp set on these cards. I love the bright colors in the paper and the little silver painted embellishments are really fun to play with as well.
Crumb Cake, Crushed Curry, Pacific Point, Tangerine Tango, Emerald Envy and Basic Black ink
Crumb Cake, Whisper White, Tangerine Tango, Emerald Envy card stock
Party Animal dsp
Party Animal embellishments