I don't know that they are all that crazy. I just know you ponder their abilities and such for hours and hours before putting the PC all together. Its all good.
Well, yeah... I try to synergize things so that they work together, so I don't lose effectiveness. The craziest idea I've had thus far was probably my Warlock5/Cleric3/Binder 1 Draconic Priestess of Lolth (5 level gestalt)
Most of the other ones are fairly 'normal', though I do spend a good bit of effort trying to make sure I'm not doing anything subpar.