@(you need an account to see links)
Jajajaja! Thank you!
I'm not really sure what images you should use. Maybe the actual forum image from the "Library" sidebar tab?
I'm not on the forums that much, but to me they seem moderately active overall. Some areas like the discussion/ forum games/item-dragon sales move a mile a second, so it's always good to consider "recent" threads to be back at least four pages.
Moderate movers are suggestions/creative corner/art sales where you can expect the place to shuffle itself by about a page within 6-12 hours, but sometimes faster.
Slow movers are in-flight discussion boards, as far as I can see. If you discount people cross posting their sales threads in discussion and bumping Flight Sales like mad.
But to be fair, I mostly only hang out in forum games/creative corner/and art sales with only the occasional dip into item sales, so I'm probably a bit biased.
That listing for gem drops looks fab! Very concise and to the point.