This site offers some tools for geohashing, in particular in relation to generating GPX files.
If you just want a single location for a given graticule for today (plus the globalhash, just in case it is in your vicinity), use a URL of the form http://geohashing-gpx.heroku.com/single/latitude/longitude. If your graticule is east of 30W and the next day's DJIA opening is available (after 13:30 UTC), you'll also get tomorrow's hashpoint in the resulting GPX file.
Similarly, if you want a single location for a given date other than today, use a URL of the form http://geohashing-gpx.heroku.com/single/latitude/longitude/YYYY-MM-DD.
If you want the hashpoint for more than one graticule (similar to what the Small Hash Inquiry Tool provides), you can use a URL of the form http://geohashing-gpx.heroku.com/multi/count/latitude/longitude, where count is the number of steps you want to go into each direction. Similarly as before, if you are east of 30W and a new DIJA opening is available, you'll also get tomorrows hashpoints.
Similarly as above, you can also add a /YYYY-MM-DD style date to the URL to get only the hashpoints for a certain date.
While it has nothing to do with GPX, it might still be useful for those people (in Germany or parts of Europe) who want to achieve the public transportation achievement. With a URL of form http://geohashing-gpx.heroku.com/stops/latitude/longitude/YYYY-MM-DD, you'll get redirected to a list of (bus, tram, train) stops in the vicinity (5kms) on Deutsche Bahn's website.
git clone git://git.alech.de/geohashing_gpx.git