Ok, all - it's been a while since I've posted anything - but I wanted to post on something that I recently bought, got in the mail today, and tested briefly to see if it would work for what I wanted it to. The short story is that it won't work for my intended need, but maybe it will for yours?
What is the item? Well - it may just be the cheapest laser range finder yet that could be adapted to the Arduino:
http://www.ebay.com/itm/131816873282
(note that link may not last forever - if it doesn't work, search for "Mini 40m Laser Distance Meter Range Finder" - and you should find something similar)
Anyhow, it only cost me $22.00 USD w/ s&h - I wanted to mount it on a servo, and scan it around, but once I had it in my grubby hands, I am pretty certain it won't work - at least not at the speed I wanted to use it at (aka - as fast as possible, for use on a robot platform moving at a decent pace).
Once I got it, I took it out of the box, popped some batteries in, and powered it up. Overall, it's a decent unit for what it is meant for (so, at least it wasn't a total wash for me), but when you put it in "continuous measurement mode", it's hit or miss whether it will return back a measurement. Even when it is running properly, you only get maybe 2-3 measurements per second at best. If you move it too much or too fast, it stops measuring. If you aim it at the wrong surface, it stops measuring (typically surfaces without a good reflection, or too diffuse, or too dark, or...). I haven't tried it outside, but since it seems to use a visible red laser (hmm - I wonder if it would work better with an IR laser?) - full daylight might cause problems.
I think (?) it uses some form of parallax measuring, like other laser tape measures (it isn't ultrasonic - it's a real laser, but not time-of-flight or phase mixed, I don't think). I was able to find the module it uses (or something similar) on Aliexpress:
(again - same caveats apply to this link as before)
Fairly easy to hook up and use serial comms it seems (19.2 kbps, 8n1). Power it with 3 VDC, 3.3v TTL serial (so level shifting will be needed).
If you look around on AEx - you can find other modules that hint at being able to take more measurements per second, but I don't know if this module can do that or not. Maybe somebody can play around with it more, if I don't get to it first.
If your needs aren't great (speed-wise), then this module might be the ticket for any number of experiments or uses with the Arduino. Hopefully someone will find this info useful.