Well a specific example would be Crystal. It's an amazing VST, you can create beautiful pads with it, and it's good for some leads too. Also rhythmical parts are good to programm with it. Anyways, there's a top list of freebies and commercial vst's on kvraudio, the link is here >> KVR Audio VST Ratings . They're sorted by GUI, Sound, Features etc. And you can choose to list either top freebies or the commercial ones.
Another good thing that just started some year(s) ago is the KVR Audio Developer challenge, where they give a prize to the winners of the best made freeware vst instruments and effects, you can see a list of those from this year here (its still in progress so no toplists for now) >> KVR Audio Developer Challenge 2007, and the toplist from last year is here >> KVR Audio Developer Challenge 2006.
Anywho, just try googleing "Top freeware VST Instruments / Effects", there should be a pretty extensive list of freebies on some forum site, I really can't remember the link rite now. Have fun!