Don't know if it was around when this thread was started, but how about
jDownloader? It's not the prettiest (or most bug-free) program in the world, nor the easiest to use, and it's Java-based, but it is tremendously powerful and there is even a Mac-specific version. (Though I note that I've actually had more luck running the generic build--the interface looks more like Windows, but it seems to behave better.)
It supports link grabbing indirectly, via the clipboard (you can set it to just scan the clipboard constantly looking for links), or directly via plugins. Handles Rapidshare queuing and downloads, along with pretty much every other file host there is.
Kinda reminds me of Azureus of old in style and mentality, and it works for me once I got it set up.