Based on a question from Steve Kirks, I've started working on a tool that would capture a copy of a Radio Userland weblog's comments on Userland's server so they could in turn be exported to another blog application (e.g. Movable Type).
I have most of the "core" import code written - the export code still needs to be written, and the new tool needs "window dressing" so someone besides me can use it. It seemed like now would be a good time to solicit some suggestions for a tool like this. If you have any, let me know in the comments.