I was browsing through Heather's list of SharePoint resources when I found this link to an RPC method that I was unaware of. That led to this article that documents the various RPC methods and provides even more links to other information.
If I'm not mistaken, isn't this just the sort of "associative trail" that Vannevar Bush had in mind all along???
UPDATE: Bil Simser has a great post on this topic that is a must read. Go check it out!