TJ’s Site News allows you to display a message on every page. Customisable message that allows html and can be turned on or off.
AnswerTips are small bubbles of information triggered by double-clicking any word on an AnswerTips-enabled page that allows your visitors to access definitions and fast facts on millions of obscure words, personalities or slang.
ImageShack Uploader allows you to upload images to ImageShack from your WordPress post screen and to insert them with the thumbnail into your post with a few clicks.
MarketingTrick is a plugin that gives access to full text of posts only to registered users, but has some additional functionalities than just to force users to register/login.
StickPost allows you to stick a post to the top of the homepage.
StickPost works great and it makes RSS feed valid with no errors. Just what I was looking for.