Laser question

[Um...Me123]

Is a laser diode work similar to a LED?  It will just send out a straight laser beam right?  Is there any way to make a laser beam show up in the air (a physical line--not just a dot on a surface) without using fog or some spray (like CSI)?
Ii am asking this because I noticed laser diodes on ebay that were fairly cheap and they will little gold colored canisters (smaller than a quarter) and had 2 straight pin leads.  They do the same thing as a handheld laser pointer?
Thanks
P.S. They have laser beam recievers dont they?  Just like infared recievers?

 

[audioguru2]

A hologram is the result of a laser beam and its reflected interference pattern of an object and shows up in mid air.

A visible laser beam is light, so can be detected with a light detector: photodiode, phototransistor or light-dependent-resistor.