TOSTW - the official Star Trek website at www.startrek.com
I recommend this site. As at autumn 2003 it has about 2,000 [Voyager] screenshots, and more screenshots covering the rest of Star Trek.
I believe TOSTW's strengths are the behind-the-scenes, interviews and production articles, details of forthcoming conventions, official fan club details, and television network schedules for Star Trek (at least UPN).
During 2003 it has rewritten its episode synopses, which I suspect they had to do because many of the old ones had factual errors; the new synopses are shorter but when I looked at a few I did not find any factual errors.
Its encyclopaedia, re [Voyager] is basic, however, with (as at autumn 2003) only about 200 non-illustrated short entries and therefore I would suggest (as well or instead) a look at my VOYCABULARY illustrated encyclopaedia which has over 4,000 detailed entries.