As you may know, Stickies isn't scriptable except through System Events. There is a menu item to export the text from a Sticky, but there is no command to export all Stickies to a text file at once. Hopefully, one day Apple will implement this function.
Until that day, though, here is a script that will allow you to export the text from all of your Stickies. A text file will be created for each Sticky that you have created. With all of your Stickies exported, you can search the exported Stickies via Spotlight, which is currently not possible unless you know how to build a stickies plug-in for Spotlight (which doesn't appear to be easy). It will not export images or movies; perhaps I will create a script that can extract images or movies if someone else doesn't beat me to it.
I saved the script as an application and placed it in the Dock for whenever I need to export all my stickies.
[robg adds: This works as described; when you run it, you'll get a dialog asking where you'd like the exported notes to be saved. Choose a folder, and very quickly, the export will be done.]
Mac OS X Hints