OK, my second thought after having this idea was "I bet somebody's done this already", so feel free to point out prior art. It was already inspired by much poking around on LiveJournal, thegraybook's hilarious Very Secret Diaries (which I finally got around to reading the other day) and jiggery_pokery's suggestions re: the release of my own fic-in-progress.
OK, for the first time since spring, the 15 minute walk to work actually did its job of waking me up. In the balmy days of summer it doesn't really work, but when the cold is piercing your fleece within a minute of stepping out of the front door, you very rapidly find yourself more awake. Question is, does this mean I can get away with setting my alarm clock a bit later?
Spent a little while refining my LJ styles - not much visible difference (except for the colour change), but it's a lot neater under the hood - no referencing of external style sheets, no hard coded colours, name etc. This allows the easy changing of the colour scheme from the "Modify Journal" page, although it's going to look funny on a non-white background (unless it's very pale) as the beveling would get messed up - the transparency allows me to work around one colour change, but not two. The header and footer are, of course, hard coded, but other than that it should be a fully portable style. Yay me!