Search for date ranges

Implement the option to search for dates less than or greater than a given date - that way I can search for stuff that's been outstanding for ages - or even between 2 dates. This could possibly be invoked by using the = < and > symbols when searching so, for example to search for everything before 1st May, I'd type in <01/05/2009
(http://cintanotes.com/forum/viewtopic.php?f=4&t=254)