Twitter is a popular short messaging service that was was used to let University of Michigan graduates put a message up on the big screen at Michigan Stadium from their mobile phones during commencement last weekend.

Twitter gets regular use for all kinds of much less grand things; the typical message reads a lot more like "I'm eating a sandwich." Here are some tools to help you look for interesting things happening locally on Twitter, using the advanced search feature that lets you hunt for what you're interested in but only returns results that are sent from within a few miles of where you want to look.

Search for nearby farmers markets

A distinctive part of Twitter is that you can inform the service where you are, and it will encode the message it receives with some level of detail of that location. That's particularly interesting when you're writing in from a mobile phone.

The Twitter advanced search tool gives a straightforward way to look things up with your search constrained by geography. Fill in the blanks to restrict your search. This search for the phrase "farmers market" within 25 miles of Ann Arbor gives the following:

cantonfun: The first Canton Farmers Market of the season is this Sunday, May 9 (Mother's Day) from 10 a.m. to 2 p.m.

psa2: RT: @ChelseaLibraryMeet the New Director of the Chelsea Farmers Market!

KerrytownA2: RT @BobNeedham: #annarbor farmers market back open on Wednesdays again for the season.

Plymouthmich: Farmers Market Opens May 8. The market takes place from 7:30 a.m. to 12:30 p.m. and runs through October.

Search for morel mushrooms

Mushroom hunting is best done in the woods. No one in their right mind is going to geocode the location of their favorite hunting patch, but some people will note what county they have picked morels in to give other hunters a sense for the season.

A Twitter search for morels within 100 miles of Ann Arbor is instructive:

• tvnewzguy: Some day I am going to hunt morels! RT @NorthGuide: Morels are up in Gaylord!!! --> RT @raysretreat Morel Season
• uclub: Featured at the UClub: Grilled Chicken with Braised Fennel Leeks and Morels Gnocchi Vegetable Medley.
• vielmetti: Pleasant Lane Farms brought morels to the Ypsi Downtown Farmers Market via @realtimefarms
• DElshoff: The rain this weekend really helped the morels! Get out and find some! For ideas and identification see North Country Morels

Encoding your tweets so that they can be searched

Most mobile phone Twitter applications have a way to specify where you are, so that when you post something it can tag your location.

Andrew Turner's notes on the Twitter location API show how these settings can be done from a command line, so if you are writing code to track something in motion or to encode the location of entries that refer to something somewhere else you have some tools.

Fast Company addresses some of the privacy issues in geolocation. Kit Eaton writes:

"The idea would be that you could use Twitter to discover the news that's really going on nearby to you, or find out events, businesses or even people--turning Twitter into a seriously powerful hyperlocal news and advertising tool."

Kit has part of the right idea, but not all of it - for this service to be useful, it needs to be more than a simple advertising vehicle, and allow people to share and discover things which are hard to find with text based searches.

Edward Vielmetti uses every trick in the book to find morels. Text the location of your secret mushroom hunting location to 734-330-2465.