I like to keep active members on the members list of this site. Periodically, I will prune "old" members based on post count and activity. If you are active on the forums (perhaps, active PM'ing) then you have nothing to fear. However, we'd love to have some posts from you as well!
Here's the list of those who will be pruned from time to time:
*Members who haven't been active for 3 months and have 0 posts.
*Members who haven't been active for 6 months and have less than 3 posts.
*Members who haven't been active for 1 year and have less than 5 posts.
*Members who haven't been active for 2 years and have less than 10 posts.
*Members who haven't been active for 5 years and have less than 20 posts.
*Members who haven't been active for 10 years and have less than 50 posts.
*Members who haven't been active for 100 years and have less than 100 posts.
If you can make it to 50 posts I think you're pretty safe.