Here's a zip with 6 holiday/winter themes for your install. They are all currrently running on my own install at HSJ. Two themes are by Ron and I.
They include as follows:
Atypical Christmas (theme options and changeable header)
Winter (theme options. I don't know why I didn't add the header option here.)
Iceburrg (header option)
Red Xmas Ornament (header option)
They *should* be okay. Just make sure to enable them on a test blog and have a look just to double-check.
I'm sure some or a lot of the code is not quite up to Luke's standards ;P, but they'll do. I found a few more holiday themes, but some need work to be enjoyable in the MU environment (TABLES in the sidebar??) and a couple were just plain ugly.
http://www.atypicalife.net/xmas-themes.zip (1.2 meg) Let me know if there's any issues and I'll fix them ASAP.
(hope this is okay Andrew)