The new Google Toolbar is in beta. Key feature is that it kills pop-ups. So, if you're still using Internet Explorer and are jealous of all the Safari and Mozilla users who don't have to deal with pop-ups, don't be. I use IE at work to achieve user empathy, so this is a tasty upgrade to what was already a cool little mini-app.
There's also a BlogThis! feature which is rapidly becoming a ubiquitous add-on to all types of client software.