Dorian,
Disk Warrior is great for rebuilding the directory (index) of your hard drive. It's not entirely necessary, I use it mainly for ordering my spare storage drives (I have multiple partitions and hard drives).
As far as my OSX drive, I stick with letting the OSX built-in utilities run the maintenance. The only problem, is that when the computer is in sleep mode, it doesn't run any utilities - it's asleep! (D-oh!)
What I DID go out and get, and has proven to be invaluable, is a nifty little scheduler application called 'Macaroni' (it's only 10 bucks or so),
http://www.atomicbird.com/ that runs the maintenance on a regualr basis. It usually will fire up about midnight - I'll be reading or working in Photoshop and it'll go off and will hear the 5 minutes of hard drive chatter as it checks and repairs permissions, and tidies up any logs and general UNIX housekeeping.
Deb.