m5-rc14that automatically (and efficiently) sections a sorted list by alphabet letters and offers a side-bar widget for quickly jumping to each section. This widget could be very useful for any project offering an extremely large list to the user, such as a music player showing artists or albums.
Some things left out with this widget are a smooth scroll to the selected position as well as a finer control for sections that have large item counts themselves. More to come later :)
Here's a screenshot using dummy data:
Licensed under the GPLv2.
EDIT 2012-08-22: This approach represents very old design patterns for Android and has been broadly replaced by upstream components such as the fast scroll mode of ListView.