I have a magnifying glass with built-in light.
I also second the scanning technique. I often find that when I scan a stamp to post here with a question, the scan itself enables me to see the answer without posting. Helps me look a little less foolish a little less often.

Stampalotapus: how does the microscope work? Are you looking at watermarks with it or does it show design detail? Also, can you post a link to where you found it -- the day is not far off for me, I fear.