Grandpa on the Go.
Family Bee is an industrial strength family tree viewer. It allows viewing of all details for individuals and families in GEDCOM genealogy files. View all individuals, family information, individual bio information, pedigree trees, descendant lists, notes, etc.
Lets you annotate your tree with on-site notes, including photos (graves, primary docs, etc.), and send them to your home machine via GMail.
The App is fast, robust, and complete. It has been tested on files up to 20MB (65, 000 names).
If you need to try before you buy, there is a fully functional (time-limited) trial version available. (Scroll down to "View more applications" to find it on the Market.)