***Banner ads may not appeal to all. How about membership levels?***
There is already levels. Like Junior Member, Preferred member and so on.
***when someone hits a threshold of number of posts, or number of quality posts, they jump to another membership level.***
Yes this already happens
***Benefits could include an expanded profile, more storage space, bigger avatar (ugh), a private forum, not to mention the esteem of one's peers. ***
That is just plain useless. I post on many boards and personally I could care less about a expaned progile, more storage space, bigger avatar.
***If you provide benefits, though, be prepared for people to "game" the system. They may churn out lots of short posts, or get their buddies to rate their threads well... ***
Not is I'm counting post. I'm sure I could set up a something (as phpbb is written in PHP which is easy to edit and add features)
***You can more or less count on a few people taking shortcuts whatever measures you use. ***
Hence the monitoring....also moderators monitoring.