In Facebook, it used to allow you to look at who are your pending friend requests and you can remove those pending friend requests respectively. However, don’t know since when this feature has no longer available. If you go the friends section, you no longer can see who are still in pending friend requests. It is still okay if you still remember who you have requested to be your friend. You can still go to our friend's profile page and cancel the friend request. But what if you have forgotten who you have requested to be your friend?
Thanks to this “Pending Friend Requests” application in Facebook. You can just go there and install this application in your Facebook. This application allows you to look at who are you pending friend request. There are 2 main tabs in this application:
(1) My Pending Requests
Click on the “Remove Request”, it goes to the friends profile page. Of course if you can also “Send Reminder” if you still want to add him or her.
(2) Remove Requests
In your friends' profile page, you can click on the “Cancel Friend Request” to cancel your friend request.
[Update: August 18 2012]: The automation of finding your friend pending request is no longer available due to the Facebook has completely removed the "friends request send" API. However this Facebook application - "Pending Friend Requests" still allow you to manually key in the friend's URL here for tracking.
Hope this is useful! Good luck and I hope you don’t get too many “Pending Friend Requests! You don't want to have too many pending friend requests as Facebook may think that you simply request even you do NOT know the person in real and possibly to get your account banned. Happy facebooking! :)