Microsoft has taken a cue from Mozilla and has made available a bunch of useful add-ons/extensions just like Mozilla Firefox over at the Windows MarketPlace.

Folowing are some of the categories for which Microsoft has some add-ons/extensions:-

Online Protection
Parental Controls
Pop-Up Blockers
Privacy
Auto-Fill Forms
Bookmark Managers
Business Tools
Developer Tools
Download Managers
Tools and Utilities
Web Feeds
Offline Browsers
Other Browsers
Animation (Flash) Players
Digital Photography
Music and Audio Players
Video Players