Im blogging about various firefox tools you can have that will help you with SEO. In my article can i say... "If you dont have firefox already you can download it here" and post one of the banners. Is that against TOS? To encourage people to download firefox... Thanks!
If by "one of the banners" you mean an AdSense banner, then yes, it's against the ToS. Referral links are governed by the same ToS as contextual ads and link units, and are considered 'ad units' from a ToS perspective. HTH, Sam