I tried searching through the forums (oh, how I miss the old site) but couldn't find an existing thread with everyone's suggestions. If it exists, can anyone point me to the link?
The usual way to do it, is through the Bug Tracker, using 'Feature' as the type of report. I haven't seen any threads about features on this forum yet.
It does rather depend in exactly what the new features are that you wish to see.
If it is new features for the Daz apps, then as Jimmy has sid, use the bug tracker, but do check to make sure there is not a requsets already there covering the feature you would like to see added, and just add a note to that.
If you are talking about features for the Website itself, then there are several threads around. This one gives some information in the first post http://www.daz3d.com/forums/discussion/115/ as does this one, although it hasn't been updated recently http://www.daz3d.com/forums/discussion/123/