I wouldnt make TOOO big a deal, its a month..so what.
Just go out for a cup of coffee
I'd be exhausted if my blokey tried to do something special every month. It would seem too forced.
But as others have said, keep it small and simple, or you'll have to buy her a yacht when your year milestone pops up.
I personally find celebrating milestones like that even odd. I dunno, I think I'll wait til marriage before I care about anniversaries.
An = year!
I don't get how you can celebrate a year within a month :P
Anywaaay, just invite her round for a film and get a takeaway or something. Keep celebrating the months and you'll be broke.