Measuring room acoustics

I want to measure/analyze the acoustics of my room. What are some cheap, easy to use options out there? I am a newbee, assume I know nothing.  What tools do I need?
REW or Fuzzmaster (or is it Fuzzmeasure) if you have a macbook like I do.

You'll also need a calibrated mic, like a Umik-1
Check these out:
RTA Audio Analyzer
Measuring your Rooms Acoustics with the Impulso App
PMIK-1 microphone
Room EQ Wizard - Very popular and lively user’s group. Free.

You will need a measurement microphone, several available via Parts-Express.

OmniMic - Currently the darling of some reviewers including Stereophile. Comes with its own measurement microphone. Designed more for speaker makers than room tuning though. I wouldn’t spend the cash unless you know you need it. :) One convenient feature is the automatic blending of gated and integrated measurements. ESPECIALLY useful for checking speaker driver response at the listening location.

Another option is Android based AudioTool for which the imm-6 is ideal. I particularly like to use this with the imm-6 to calibrate my HT system for volume settings. Much more convenient than a PC based set up. :)
OH, and this one also was made popular by a few mentions in Stereophile, know very little about it:
Awesome, thanks very much people.