I saw this tip the other day on twitter from Luca Massaro (http://twitter.com/iamluca). It's a way you can enhance your searches on search.twitter.com, you can narrow down your searches to look for something more specific.
If you type near:"London" within:10mi coffee it will then show you for tweets that are within 10 miles of London and they have mentioned coffee.
As you can see it can help you create some very custom searches.
I am always interested in feedback so feel free to add any comments, or you can mail me here, also if you would like to submit a quick tip with full credit and links back to your site then also feel free to contact me.