Invite all your friends to like a page at once
Spamming sucks, so use this one sparingly. Open up your console in Firefox with the command Ctrl+Shift+K. A window will appear where you can enter the following code to avoid inviting people one by one:
Block obnoxious app invites
If you've had it with all those Farmville invites from your freshman-year roommate you don't have the heart to unfriend, there's a way to banish them for good. In your settings, click "Blocking" on the left-hand bar and type the name of your invite-happy friend(s) in the "Block app invites" section.