I picked up a Bosch GLL 3-80 a couple of months back.  Also got the telescopic pole accessory.  I can't believe I lived as long as I did without this.  

There are so many things this will save you time with, if you use your head.

My favorite application is lining up speakers on can lights or other fixtures.

I also use the horizontal laser to set all of my wall box heights.

Lots more, but thats up to you to figure out!