doppelganger/mindspy help?

[he-man diceroll]

so, a friend is starting up a campaign up and I've been looking at a doppelganger(as a class)/mindspy. but cant find anything to work with them in between and after. core books and complete are accepted, anything else is on a case-by-case basis on the dm's digression. any good classes that work with both of those? oh, and item loadout suggestions are welcome too. i think starting level is going to be about 4-5.