If you want to remove the PeepOpen icon from the dock and also when you do Command+Tab, you can easily do so by editing it's Info.plist.
vi /Applications/PeepOpen.app/Contents/Info.plist
# somewhere in the bottom, before the </dict> tag paste the following:
<key>NSUIElement</key>
<string>1</string>
Now it won't show up anymore! :D