Regarding 3: I live in a smaller city, and it regularly takes a while for location based web stuff to catch on around here. I sign up for them, but since thres

Regarding 3: I live in a smaller city, and it regularly takes a while for location based web stuff to catch on around here. I sign up for them, but since thresholds of usefulness take a while to be met, I completely forget about the service -- then one day I'll hear about it from someone local, decide to give it a try, and rediscover my existing account. As such I like the occasional email reminding me of the existence of these things. Preferably something in the form of: Hey, thanks for signing up. We are still waiting for more people in your area to sign up, currently there are only n users, which doesn't quite meet our threshold[1]. We just wanted you to know we haven't forgotten about you. If you have any suggestions on how to get more users near you, let us know! [1] alternately: n other people are using it, spread the word and get even more! A frequency of once a week on that seems pretty reasonable, rather than once a day. In this particular situation I think a balance between "forever alone" spam and "hey, we still got your back" emails is a nice goal.