There are lots of ways to make it more interesting and useful...for example, the website can have a database of female musicians categorised by instruments, etc. If you wanna, can even do a simple profile page or some forms for them to fill up and add their info to the database. Then you can also have a sounds/music section where you can feature any form of music/samples, etc contributed by the members...can be anything...originals, demos, short clip of themselves doodling on their instruments, video clips, etc. Every week you can showcase and rotate a member's work, or do a short interview, etc just to spice things up. Of course, once you start to organise gigs like ladyfest, etc you can incorporate them in...advertising/promoting them.
Well, let it slowly grow into a community and it'll work itself out
I have other ideas, etc and perhaps will contribute more via pm or something.
The start is always difficult at first...ideas and concepts can sound promising and exciting but execution can be hard...take a few small steps at a time and see how it goes
Good luck!
P.s Yeah, I'm saying so much cos I'm also looking around female band members to start a side band and such a website would greatly help *lol*