Update April 10th 2013. Facebook is limiting the number of invites you can send at one time. 100 at a time and each event can only have 300 pending invites. Total! Total BS is more like it.
Facebook Invite All Friends Chrome Extension – Ok, first let me say that there is a way to invite all friends to an event or like a facebook page. There is just one pre-requisite, you must have Chrome. Chrome is Google’s own browser. There is anything wrong with Chrome… most people do not use Chrome. Install Chrome from here.
Once you have Chrome installed and running you need to install this Chrome extension available from the Chrome Web Store. This Facebook Invite All Friends – Chrome Extension 2012 Application works well. It can overcome hours of clicking and inviting.
Here is a video clip showing the plug-in in action