Using the Coordinate Calculator
The Geohashing Coordinate Calculator is a wonderful tool for finding the day's geohash without having to know anything about the Dow Jones Industrial Average, coordinate geometry or md5 hashes. It was written and is maintained by Zigdon. The application should be pretty self-explanatory, but here's a feature guide.
 Basic Instructions
In the box at the bottom left, enter the date of the geohash you are interested in, in the format YYYY-MM-DD, e.g. 2008-10-31. The default graticule is Boston, but you can click the minus sign at the top left to reduce the scale, then click and drag to see anywhere in the world. When you click on a graticule, a red line will appear around it, and a red inverted teardrop will point to the day's location. You can click the plus sign (top left above the minus sign) to zoom in and see the location more clearly. Hint: once you have selected your graticule, click the Set Default button. Next time the map will come up already at your graticule.
 Different Views
The buttons at the top right allow you to chose what sort of map you see the coordinates on. The default Map is a street map. You can switch to a Satellite view showing you what the area actually looks like, at various levels of zoom. Remember that what appears as a vacant lot in the satellite view may now be a factory, and what appears as a row of houses my now be an office building. The Hybrid view combines map data with satelite data, so you can see street names while looking at the actual picture. The Terrain view shows elevation through contour lines. The closer together the lines, the steeper the hill.
 Map Links
With your graticule selected, its name and coordinates should appear at the top right, and the name should appear again in the bottom left, as a clickable link to the wiki graticule page. If there is no name given or the link goes to a non-existent page, you can create one. The Meetup link will take you to (or allow you to create) a page for documenting or planning a meetup at that location and date. The Day link takes you to the expedition archive page for that day, listing selected expeditions reported or planned for that date around the world.
One you have scrolled and zoomed around the map, if you want to save or e-mail a link to the result, first click Link to this page, then copy the URL out of the navigation bar in your browser. If you copy the URL without first clicking Link to this page you will get the URL of where you started exploring the map, instead of the area you found.
The application uses Google maps information, and if you want to use other features of Google maps, such as getting directions from a particular place, the Google map link will take you out to a regular Google map interface, with the geohash location already selected. The Nearby food link simply uses the Google database to search for restaurants near the geohash.
A link at the top left leads to this wiki Main Page, so that people who are wondering what this map is for can come and read about it. The active graticule map loads a list of all the Active Graticules listed on the wiki as links to their position on the map, along with an estimate (based on User tags on the graticule page) of the number of users active in that graticule.
 I'll Be There
The map has the ability to keep track of who intends to visit the geohash. Click the red teardrop and it will ask you if you plan to be there, Yes or No. Many people geohash without ever using this feature, so don't take it as a definitive statement about whether people plan to be at the geohash.
 Alternate Meetup Locations
Some graticules use this tool to select and vote on alternate meetup locations when the random one is inaccessible.
If you click and drag the red teardrop to a new location, when you release the mouse the red one goes back where it came from and a new, green teardrop appears. Click on it, and you have the opportunity to submit it as an alternate meetup location for the graticule. By suggesting it, you are saying that you will be there.
Once an alternate meetup location has been proposed, it appears on the map as a blue teardrop. If an alternate location is proposed for your graticule, click it for the opportunity to say Yes or No to whether you will be there, just as you could for the default location.
The most common complaint is the message "Market data is not available for YYYY-MM-DD." This usually means what it says, for one of the following reasons.
 Too early in the day
The market data becomes available at 9:30 a.m. Eastern Time on the date of the geohash. If you are east of the 30W meridian the application will automatically use data from the Dow opening the day before. You simply cannot know what the geohash location will be until the Dow has opened on the appropriate day. Geohash locations for the whole weekend: Friday, Saturday, Sunday, and any holiday Mondays, become available as soon as the Friday data is out.
 Incorrect date format
Note that the entry format for the date is YYYY-MM-DD. That's the ISO 8601 format, not the American. The calculator will not be able to interpret an incorrectly entered date.
 Too long ago
 Market fluctuations
Occasionally, when there have been extreme changes in the stock market the day before, the coordinate calculator will not show a position until as much as a couple of hours after the normal time. Other sources may show an opening value, but don't trust them! This is because some values are estimated in the other sources. The estimate may be good enough for investors, but a change in a decimal place near the end can send a geohasher right across the graticule. The location relative to the north or south of the graticule is not a function of how high or low the stock market is: it's much more complicated than that. Wait patiently for the data to be available to the Coordinate Calculator.
 Map not visible
If the map does not appear for you, perhaps your web browser is too primitive or you are missing a plug-in. I'm hoping someone will edit this section with the software requirements to use the coordinate calculator.
 More Information
The author's talk page is the clearinghouse for feedback on the application.
Discussion on late release of coordinates.