Most forums, if not all, have the "Recently online users" on most of these softwares you can change the timeframe. What timeframe do you think is the perfect amount for a community? 10 minutes, 20 minutes, 30 minutes, 1 hour, 24 hours?
Why do you choose the amount of time you have, or why do you like the default time?
Why do you choose the amount of time you have, or why do you like the default time?