I think it's good to start with nicknames or shortened versions and then add you own endings, just so they can be shorten to something normal but are still unique.
Thats said the reason a name isn't heard of tends to speak for itself. Most completely made up names sounds like medicines
Or you could use a word associated with something else like Apple.
If it was me though, and i REALLY wanted something unheard of then i'd check out some fantasty book characters.
I made up a name - Rhaen, pronounced "rain" or "Ray-en" (not quite decided how to pronounce) that i really like but there isn't a chance in hell of my hubby letting me use it.