I recently bought the Bosch DLE50 - so good, I wish I bought one ages
ago.

http://www.screwfix.com/search.do;js...+laser&x=0&y=0

In practice, measures down to about 250mm - which is the only
shortcoming I can find.

Has a simple press button to change the measurement reference point
from the back edge of the box (the default, and what you'd naturally
do for any internal measurement), to the front edge, to a little pop
out spike(for getting into corners), to a tripod point (can't see me
using that one).

Checked accuracy with tapes at all sorts of distances, better than
their spec.

Didn't think I'd use the area and volume measures, or cumulative
memory - but they've made them very easy to use, so I do.

It was on offer at my builders merchants (Ridgeons) so paid less than
the Screwfix price and got a quite reasonable free watch (which will
be somebody's crimbo present).

Where it comes into it's own is the places hard to measure accurately
with a tape on your own - and you want to measure several spots to
pick out the narrowest point etc.

I did wonder if I was "over-buying" something that would get limited
use, but I'm finding it gets used a lot - above all because it's
supremely easy to use - and quick.