I have a basic bosch laser that gives me a straight line on a ceiling and down the wall to help line up in-ceiling speakers etc when doing retrofits or sometimes pre-wires.  I love this tool as I hate trying to measure off walls that can be off-set etc.  when the electrician throws in can lights that are not in a straight line its handy for mapping out a happy medium that looks balanced visually.  I'm thinking of stepping up to something that can give me cross-hairs on the ceiling if it exists. Anyone have a favorite laser tool they like?