I have been known on occasion to host a poker night. Typically these are an invite only affair. Depending on the attendees, it will be for some small stake of money ($5-$10), but more often than not there is no buy in (although people are always encouraged to bring snacks to share).
I model this game night on one run by my friends Mark and Charley, and so some things may be different from other poker games you've been involved in.
For a full list of the house rules and variants generously imported from Mark and Charley's poker night, I refer you to Mark's wiki page on the subject, available at http://www.querki.net/u/jducoeur/poker/
For a primer on the rules of poker, including a listing of the ranking of poker hands, I refer you to the pagat page at http://www.pagat.com/vying/pokerrules.html.
You might also look at boardgamegeek's page at http://www.geekdo.com/boardgame/1115 for some resources.
If you are curious as to the history of poker, see http://www.pagat.com/vying/pokerhistory.html.