I came across this list of very interesting stuff below (and it could save lots for time)
1. Faceted Search: http://facetedsearch.codeplex.com/
2. Podcasting Kit for SharePoint: http://pks.codeplex.com/
3. Knowledge Base: http://spkb.codeplex.com/
4. SharePoint Branding Tool: http://brandingtool.codeplex.com/
5. SharePoint User Account Control: http://spuac.codeplex.com/
6. SharePoint Enhanced Calendar: http://spenhancedcalendar.codeplex.com/
7. Enhanced Discussion Board: http://edb.codeplex.com/
8. Wildcard Search: http://spwildcardsearch.codeplex.com/
9. SharePoint Usage Logging Kit: http://sulk.codeplex.com/
10. SharePoint Zip: http://sharepointzip.codeplex.com/
11. Facebook Kit for SharePoint: http://fks.codeplex.com/
12. Short Messages: http://spmessaging.codeplex.com/
13. Color coded calendar: http://planetwilson.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=11814
14. Most Popular Pages on SharePoint: http://popularpages.codeplex.com/
Thanks to my two bits heput the list together