I've uploaded a slightly revised version of Surftrackr. As ever, you can get the latest (and previous) tar-balls of the software from the download site.
The changes include:
The mime-type is useful because I will be able to develop a report showing (for example) all graphics downloaded by a user, and create graphs of the type of information downloaded. Graphs will probably not use Google's Chart API, since it seems a bit awkward to get it to behave as I'd like it to.