From
macosxhints.com:
Open Automator.
Highlight the iPhoto actions and drag the Ask for Photos action to the right hand pane.
From the File menu, choose to Save As Plug-In and make sure you select Script Menu as the location.
Then, when you have the system wide Script menu activated (use Applescript Utility to do so), you will have the option to select an iPhoto Browser from which you can pick any photo(s) in your iPhoto Library without having to first launch iPhoto:
Could be useful for any OmniGraffle users who wish to insert images from iPhoto into OmniGraffle.
P.S. You can do the same for iTunes as well.