PocketPC City CE - Has popular listings for all types of Windows CE software.

ZDNet.com's CE Downloads - Has many categories of Windows CE titles to choose from including software for other systems including Pocket PC titles.

Tucows WinCE - Lots of different Windows CE titles to choose from.

Grundle Software - Has a few Windows CE titles available to download including SoundWidget, PocketSwap, SpaceHogCE and CoverMe!