OpenStreetMap Diaries via a GeoRSS Box Filter

OpenStreetMap has this nice feed of its users' diaries, so that you can get all excited about the progress that fellow mappers have done near you. Now if you actually try to follow that feed, you may notice, as did I, that the problem is in the word near, which is the missing piece. It does not help to learn about new developments on another continent.
Fortunately (and unsurprisingly) the feed is GeoRSS so we can filter its contents based on the coordinates supplied with most diary entries. I did not find such service on the Web so I wrote it myself: a GeoRSS Box Filter. You say geofilter.php?url=...&minlat=...&maxlat=...&minlong=...&maxlong=... and it filters the given feed according to the given bounding box. If you omit the url, it defaults to the above mentioned OSM diary feed, and the bounding box defaults to Czechoslovakia.
More examples? How about the United Kingdom? or Georgia? (The Export tab is handy to get the numbers, BTW) To watch for uploaded GPS traces, use geofilter.php?url=http://openstreetmap.org/traces/rss. I wonder what other interesting feeds you can find to experiment with (but I did not try anything else than RSS 2.0).
Oh, and I worked on this all on the company time because it's Hack Week₃ now, yay!