I haven't got too much to offer in the way of downloads, but what I do have I am happy to share!
From the official Total Drama Action website, these "Do It Yourself" packs contain a picture of each cast member from TDA, a picture of their name in TD font, and a background. I have condensed them to save you guys time, so this one .zip file contains all the characters, their names, the backgrounds, the two team logos, and the show logo.
Note: This only contains the cast members from Total Drama Action, so there's no Alejandro, Sierra, Ezekiel, Katie, Sadie, etc. because they weren't in Total Drama Action.
From Episode 3, "Super Crazy Happy Fun Time Japan," here are the commercials that each team had to produce for Chef's fish tail candy. Contained in each .zip pack is each of the commercials in a separate video and a medley of all three in an .mp3 file.
Download .WMV Video Pack
Download .AVI Video Pack
Animated .gifs from cartoonnetwork.com: