I think these are really needed as we have about 15 members but only 5 of us are actually active.
Every week or two maybe just add a thread and people sign it and anyone who doesn't is moved into an "inactive" section of the roster or kicked out of the clan completely (depending on the person and how much they've contributed to the clan).
Also, so support the idea further, i checked out some of our "clan members" profiles. Turns out nearly all of them have either never posted on the forum or are actually in another clan and havent told us.