Thanks guys.
Question: Isn't Mega Man: Maverick Hunter X just a re-release of Mega Man X?
Indeed it is.
While I'm posting here, I may as well give my suggestions as well (The PSP is one of my favorite systems). I'll try to not mention anything anyone already has.
-Corpse Party (Horror)(PSN digital download only unfortunately) <---Awesome horror game, goes on sale on PSN every so often.
-Corpse Party: Book of Shadows (Horror Visual Novel)(PSN digital download only unfortunately)
-Gods Eater Burst (Monster Hunting) <---Fantastic, one of my absolute favorites on the system.
-Metal Gear Solid: Peace Walker (Has cross-save with the HD PS3 version, which is pretty awesome)
-Phantasy Star Portable 1 & 2 (Action RPG sorta things)
-Valkyria Chronicles II (Strategy RPG)
-Z.H.P. Unlosing Ranger Vs Darkdeath Evilman (roguelike)
The PSP has lots of fantastic ports/remakes too. Most of these are actually different enough from their console versions to be worth getting. I didn't recommend any straightforward ports of console games since you didn't seem interested.
-Final Fantasy (Visually enhanced port)
-Final Fantasy II (A port/remake of the Famicom game we originally didn't get)
-Final Fantasy IV: The Complete Collection (Has an enhanced port of the original FFIV, plus FFIV: The After Years, as well as a new scenario set between the two games)
-Knights in the Nightmare (Strategy RPG meets bullet hell sorta thing)(This is a port of the DS version)
-Mega Man Powered Up (Remake of the original Mega Man with improved graphics & other new stuff)
-Metal Slug XX (The PSP version is pretty cheap, and I like all the additions to this version, I'd recommend it)
There's lots more good stuff left that I haven't mentioned yet, but I didn't really want to recommend too many games that I haven't even played (I already mentioned a few).