Have someone in the band set up an ftp server on his computer. Use it to upload and download files, and also to keep them in one central place. Here's a quick checklist:
1. Decide who's gonna run the server. Pick someone who leaves his computer on all the time.
2. Set up a dynamic dns service on his computer.
Here's a pretty good list of dynamic dns providers. Setting up dynamic dns will allow you all to use a name (like ourband.dnydns.org or ourband.d2g.com) instead of an IP address that might change.
3. Get yourself some FTP server software. If you're running Windows XP, it's built in (it's called IIS or Internet Information Services), but it's kind of tricky to use.
Check out download.com for some freeware or shareware servers. I use Serv-U.
4. Set up hard drive space (maybe you could all pitch in for some extra storage for him) on the server computer, install the FTP server software and create usernames and passwords for everyone.
5. Get FTP clients for everyone else. A web browser will work, but I prefer a more full-featured FTP client, such as WS_FTP (which is free) or FlashFXP (which isn't free but totally rules).
With this setup, folks will be able to upload and download files from a central location. And that's just the beginning! You could even start a website on his computer, using Windows XP's built-in IIS or a free webserver like Apache. There are more and more uses for an internet server, you'll wonder how you ever did without one.