Hi John,
I've written a small program to do just this.It runs as a service (using SelfService) and at fixed intervals it collects the names of the databases to backup (as that may vary over time). Then it issues a backup command (using prop:sql) for each db and dumps the .bak files on the server. From there they can be copied, mailed, ftp'ed or whatever. Not very hard to do.
I'm using SQL Server but I guess you can do it for other flavours as well.
Peter