Mine are located here:
Macintosh HD-->Applications-->Adobe Photoshop CS-->Samples-->Droplets
Then there is one folder with Photoshop droplets and a second one with Image Ready droplets. These correspond to all the items in my open with dialog. Although, you said you deleted the application folder so I don't know why these files would not have been removed.
If this is not where the files are, try searching your hard drive for the word "photoshop" or "droplet" or the name of one of the open with apps, like "Make Button.exe".
Also, if these files are gone, you may just need to logout/login or restart for Mac OS X to realize the applications are gone, and then it will delete them from the open with dialog.
Hope this helps.