What is the best way to export iphoto library to a certain folder structure? I have done a lot of processing to my iphoto library (organizing events, etc) and I want to export my iphoto library to a external hard drive but I want others to see the files so i don't want to just store the iphoto library package.

Is there any ability to export in certain patterns like

Photos / [Year] / [EventName] /


or something similar to this?
Yes. Couple of possibilities


If you have the latest version of iPhoto 11 there's a limited option in the Export dialogue. (File -> Export. Note the 'Subfolder Format' option in the Export dialogue. Remember you actually have to have an Event selected for the option to appear)
For earlier versions, or more granularity, Apps like iPhoto2Disk or PhoShare will help you export to a Folder tree matching your Events.