Someone asked me if it was ok to sell/rent Netbuilders sigs
I'm sure we've discussed it, but as I can't find it I figured I'd mention it here.

The answer is, sure, go for it
NB sigs are do-follow. If you can get paid for it, can't see any overwhelming reason to prohibit it. This forum isn't really so large that doing so will create any huge problems, so if you can make a buck off renting a sig, no problem. We have no rule against it.