Well, you could mine coins like XTL or SUMO, but there's nearly no exchange where you could sell those..
Best choice might be nicehash or some mining rental services..
I dont think you can mine either of those coins with an x3 as they have forked to another algo. Unless there is something we dont know about the x3.
NICEHASH removed crypynight algo on new ver.
It is death for X3 on nicehash.