This has never been a very active area. Too bad. I think Beliefnet could use the leavening. Be that as it may...

Your best bet for a Thelemic lodge is probably a camp or lodge of the OTO--Ordo Templi Orientis. Unfortunately, unless you live in a major city or near one, you're unlikely to find one of those.

Any Thelemite I've talked to (admittedly not many since all my contacts have been online) was an ex-lodge member. Like most clubs, lodges are primarily useful for establishing social contacts, or so I was told. So, if you're the social type interested in meeting people, a lodge or camp may be useful.

Otherwise, there are so many terrific books available today--even a few explaining the structure of magickal lodges--that I don't know that I'd bother with a lodge myself even if I lived somewhere near one. But then, that probably testifies to the fact that I'm not much of a joiner and never have been.

Can suggest some useful books if you've not already acquired those.