http://www.stackedpoker.co.uk – Don’t use it in the link code (you can use it in your anchor text, but you will be wasting valuable space where you can put keywords)
http://www.stackedpoker.co.uk/ – Don’t use it
http://wwwstackedpoker.co.uk – you can use it but dito what Joe Deeds said.
http://stackedpoker.co.uk/ – You can use it but I don’t recomend it (I recomend it should be a permanent 301 redirect to your www. version anyway)
http://www.stackedpoker.co.uk/ – Perfect.
The http:// is necesary. The www. is best for consistency since most directories (and people linking to you independently) will use this version. You want all your links pointing to one version of your URL not two (unless different pages).
Remember that this is the URL you should put in the code of your link. This is not the same as the anchor text of a link. Be sure to select a good anchor text as that is one of the most heavely weight factors for google.
The text “Top 3 European Poker Rooms” is your anchor text. Make sure to pick good keywords for this text.
The title atribute in the link tag helps for accesability but is not necesary (I try to use it). When you put your mouse over a link the text in the title atribute of the link will appear.
Best Regards,
Nicolas