TLDR; Constantly update the limit on the number of available rewards for the early bird category so that you're always 1-5 away from the limit to make people feel urgency.
So I'm running a Kickstarter campaign selling a book called Computer Engineering for Babies. And I got an email from some guys that have a robot to basically do this automatically for you, but I couldn't understand what they were trying to pitch me, and feel like I kind of had this realization on my own. So let me have this joy of being the umpteenth person to discover the wheel ;) (btw the company that does this automatically is called stocklimits, and I have no affiliation with them, and have no idea if their product works or not.)
I did a little test this morning and just increased the limit on the early bird category from 120 backers to 125, creating 5 new slots to get the book at a 5% discount. And within like 5 minutes I had like 5 new backers. I was blown away, so I tried it again, and within 15 minutes I had 5 new backers. Now this was pretty impressive considering that things have really slowed down; I'm on day 5 now of the project. It kind of felt like I was on Day one again refreshing the page every couple of minutes to see the numbers jump up.
I also hired a guy to try to run some facebook ads, and the ads just started running last night, so it very well could be all the extra sales are just from an increase of Facebook traffic from that and not from my little "hack." Unfortunately, the analytics dashboard that Kickstarter gives you leaves a lot to be desired. I am going to try to write some scripts to basically ping my Kickstarter page every minute or two in order to get finer data to validate if this little hack works and to what extent. I'll let you know, but for now I am pretty excited.
Link to my project if you want to check it out: http://kck.st/3DtIXhQ
Edit: After doing some more tests, I think that I jumped to conclusions. The big driver for me right now are these Facebook ads. And playing with the "limited quantity" doesn't seem to be having a 2x result like I thought.