Pocket PC Techs has one of the best, if not the best non-adhesive screen protectors in the market.
The
AG will cut out glare and greatly improve the writing surface. The
C2 is crystal-clear and has very accurate colour reproduction. If you're undecided between the two, you can always order an AG/C2 combo pack.
They aren't cheap, but I still believe they're worth a lot more than any 12-pack you can get from your local department store.