women like cleaning stuff? oh my god. NO, no no no nooo!! Do YOU like hoovering? No. neither does she. Maybe if your gf seems to be cleaning a lot it's because you don't do any cleaning. That, or she has some kind of obsessive compulsive disorder.
As wildfire says, maybe get a new fancy hoover for BOTH of you to use, but not for her birthday.
ok enough lecture..
The gift depends on her.. does she like romantic gifts? That is, roses, jewellery, a nice dinner, being treated like a queen the entire day, that kind of thing.
Or does she like practical gifts. No, not a hoover. But, say, an mp3 player, or a new watch,
something that she'll enjoy for a long time.