if you're not too particular, get a pair of handcuffs, a ball gag (you know, something like a strip of rubber with a ball to put in his mouth and you tie the strip of rubber around his head) a small leather whip or maybe a small wooden paddle (ping pong rackets come to mind) hehehe.
I'm not up for these things, though. some guys are a bit more adventurous with the ropes and tying the hands to the feet then forcing your cock into him, but that's not for me.
My most adventurous fantasy would involve a sling hehehe.