HI Terri
I haven't found a 'Feature Request hub' per say, on Topliners.
If you want to review FRs that have been logged by users in Topliners, simply search on key words 'Feature Request'
If you want to create an FR, see http://topliners.eloqua.com/community/do_it/blog/2013/11/13/how-to-submit-a-feature-request#comment-28999
Best,
Zainab