I maintain a motor racing archive as a hobby. There's always new photos to catalogue and newspaper / magazine articles to identify and chase. My current task is collating Spedeworth ministox results from the early 1980s.
Other than that, I write (am working on a novel as well as some Babylon 5 fan fiction), paint (mostly watercolour as it's less faffy with cats), sew (soft furnishings, cat show drapes, decorative applique), and at this time of year, there's always foraging, followed inevitably by jam, jelly and chutney making.
I've also a scratch modelling project that's currently on hold until I can find some suitable materials to work with.