After using the Pocket PC for awhile now and looking high and low, here’s what I’ve come to the conclusion as to what some of the best and most useful pocket PC readers are (in order of usefulness):
µBook - http://www.gowerpoint.com/ - One of the best all around readers. Supports several file types, auto scrolling, annotations and highlighting. It’s fast, skinnable and free. There is also a full desktop version available.
YanCEyWare Reader - http://www.yanceyware.com/ - If you’re LDS, this scripture reader is the best. Fully featured, but only works for books in the .ybk format. It’s also free.
Vade Mecum - http://vade-mecum.sourceforge.net/ - The only eBook reader that reads the Plucker (http://dave.pluckerbooks.com:81/) format. It supports highlighting, annotations etc. It’s still in Alpha, but it’s the most stable alpha software I’ve ever used.
MobiPocket - http://www.mobipocket.com - Commercial software. The standard reader is pretty pitiful as far as features go, but it opens several formats and you’ll find lots of content geared specifically towards this reader. There’s a pro version for $20 but I haven’t purchased it.
Microsoft Reader - http://www.microsoft.com/reader - Slow and bulky and a pain to install and authorize. I personally can’t stand this reader but unfortunately many eBooks you purchase only work in this format because of DRM issues.