For: Themes and games
birthdaypartyideas.com Dora? Pirates? Princess? Click on any of the 150 themes to see other moms' tips, complete with games that were played and what won kids' raves -- and rants.
For: Decorations, supplies, and favors
celebrateexpress.com True one-stop shopping for paper plates, prizes, balloons, and more, in licensed themes like Backyardigans and original ones like pink poodles in Paris. Order prefilled favor boxes, $4 to $5 each, and skip a night of stuffing goody bags.
vistaprint.com Get the same cool options that other custom-invite sites offer, like uploading your own design, for just $8 for ten.
For: The cake
cakesacrossamerica.com Whether you want a simple chocolate cake or one with a collage of photos made of frosting, this site delivers, at $58 and up for a ten-slice cake, with a day's notice -- perfect for eleventh-hour planners! You can also order cupcakes, cookies, and pastries like eclairs and cannolis for the adults.