First Method: (Tested in 2012)
After googling a few mints i got the way to find the friends pending request that you sent to others on facebook May 2012. This way work for me 100% correctly. All you have to do is install some scripts on your browser and it will show you a tab of pending requests near you Logout section (Top Right Corner). Here are the steps...
For Chrome Users:
1. Go to http://www.unfriendfinder.com/download and click Download & Install.
2. Accept warnings to download.
3. Restart Chrome and That's it. (may be you need to login again on facebook)
For Firefox Users:
1. Go to https://addons.mozilla.org/fr/firefox/addon/748 and install Grease Monkey script.
2. Go to http://www.unfriendfinder.com/download and click Download & Install.
3. Accept warnings to download.
4. Restart Firefox and That's it. (may be you need to login again on facebook)
Note: http://www.unfriendfinder.com/download will automatically detect your browser and show you the script accordingly so no worries.
if this solution do not work for you then try multiple quires on Google like: