In reply to monkey1:
I've done 1st (or was it 2nd?) pinnical rib (S) on the east face of Tryfan in the pouring rain, which was good fun. the little crux pitch can be quite tricky as it's pretty polished, but can be overcome by 'combined tactics' if need be. Brynt's gully in Llanberis pass is a good wet weather option (depending on how wet you want to get!), and is a great 300m 2/3 ghyll scramble, although i'd avoid it if it's really wet. Lockwoods chimney is another great wet weather route, about S i think, and goes up the inside of the mountain for the most part. It. down near that lake at the bottom of Snowdon on your right as you head out towards Tremadog.
If you want to stay dry Tremadog is often a good bet, and if it does rain Striptease is a good VS that stays dry for the first pitch, after which you can abb off.
Mike