I mentioned Microformats briefly when I blogged about OpenID previously.
I just wanted to touch on them again - as they are proving to be very useful in a number of situations. Imagine you have a webpage (such as the about us or contact us page on your site) with your name, address, email and telephone number on it. Right now your expecting the visitor to your site to copy and past them into their contacts / address book if the information is useful to them.
With microformats you "tag" the data to give it context. ie. You mark up in the HTML that the data is of type "email" or of type "name". So now its able to be consumed as information and not just data.
Using a tool such as Operator which is a plug-in for Firefox any visitor to that site now knows there is information on that page of a certain type. ie. "Name" and "Email" and the plug-in allows your user to consume that data more easily and readily. ie. they can auto copy it into their outlook contacts or view your company address on a google map etc.
All nice / cool functionality.
However, real power can be derived from this type of solution when you start to enable a lot more data.
eg. Imagine having a web app generate a report which displays customers with name, address, total spend to date etc..
You can then use this technology to "mashup" the data results with google maps and get a view of where your customers are geographically located and when the "hot spots" are regarding your most revenue generating locations.
The possibilities for these "mashups" are endless.
The really interesting stuff though is that Operator is being developed by Mozilla (the people who brought us FireFox) and it doesn't take a genius to see that sooner or later this type of technology will make it into the browser iteself (and not require the plugin) which then opens up a whole world of visually rich data display and content interaction.
Or what about if Adobe's Apollo started to use Microformats - now that would be interesting. :-)
If your in the web apps / development game - I would recommend taking a look at Microformats over the next couple of months.