Don't do it! That type of advertising is EVIL!
At least only do it for non-members, if you really want to do it.
I know that if I see them within the text, I'll certainly be reading here a lot less often because they are extremely annoying and distracting to me.
[added]
If you already have them installed, I guess I'm not seeing them. Must be my adblock plus.
So...carry on!