Any winter climbing I manage to do, especially in the Lakes! I think the fact that conditions are so fleeting makes it feel even more special when you're on a route. Particularly memorable winter routes: Tower Ridge, No. 3 Gully Buttress, West Buttress (Beinn an Dothaidh), Clogwyn Du Gully Left Hand, Dollywaggon Chimney (minor epic). Bigger stuff: getting to the top of Mont Blanc without puking and a winter ascent of Mount Fuji in beautiful weather. Also, loads of great days out on Yorkshire Grit and (my home turf) the North York Moors.