A friend of mine has a cool red laser-pointer throwing crosshairs on his SB table.

Seems these cool gadgets are not particularly expensive - $40?
How truly useful are they?

Most comment on the subject I've found (in Archives) dates back five years
so I'm wondering what the state of art...of thinking is.. re. these wonderful gadgets.. today in 2011
now you guys have had a chance to mess around with them

Are they as wonderful as they look?
Does any particular make/model stand head and shoulders above the crowd?
How to get power to them? (batteries inside the unit?)