No 2. Category cloud widget

This handy widget displays the categories of your blog as tags in the sidebar. The categories or tags which are more clicked on your blog are displayed in larger fonts as compared to the relatively unpopular ones.

Go here to download.

No 1. News ticker FX

Claimed to be one of the most advanced news ticker on the web, this widget displays the latest news with autoscroll functionality. It is completely XML customizable. It also supports external RSS feeds.

Go here to download.