The homenode yes, or if your node is really good you could advertise through your signature.

I've been doing that for a while, while being kinda active for the community, and it turned out positively with no negative reactions so far -- but honestly all I did was just put the link in my sig so it wasn't really advertising in the commercial sense :)

Also worth to mention, I did't do it for the XP but I wanted people to comment, give advise, give links to useful modules, tell me I suck, whatever.

And just to make use of this opportunity, it was all about this node. Click :).