WordPress MU

Hello all,
i want to ask if any use advertising in his wpmu and what advertiser use. (Adsense, adbrite...)

And one other question. How can i put a banner in the top of all blogs in wpmu? I have seen to modify wp-admin-bar but hide the top of all themes (it can be fixed modifing the top of all css themes) but... any know how can i put a banner in the top of all blog and no modify all the themes?

(sorry for my english :S)

I just use Google Adsense and offer it as a Widget for my users.

To add it to all of your themes, just add the code to the wp_header function call. (I think that's what it's called.)

But, this call modify the headers of the themes?

I want to say if when you insert the banner, the banner covers the header of the theme.

And Drmike, can you tell me a example of blog with this advertising? (i was looking for in daria and i didnt see anything)

has anyone added advertising to the admin pages? this would be adverts targeting the blog owners as they are logged in and working on their sites...

yay! good ideea :)

But, in the case of adsense, would that possibly violate their TOS?