My site gets loads of hits from poker sites

I have a problem. My site does actually.

Lately (since yesterday) these poker sites (probably from the same company/organization) “refer” to my site. I check my logs and see tons of these sites as referers. Sometimes they spam the blog comments thing, but I’m guessing that’s automatic. This doesn’t happen very often though. I’m just wondering what the heck this is supposed to be. They refer a lot of traffic to my site - what’s in it for them? It’s not like anybody sees my logs and visits their sites. :huh: