The modern Olympus use a digital photography-specific 4/3-sensor,
and is often a lot lighter for it, compared to it's natural competitors.

Megapixels are no longer really a criterion,
with even compacts and many cellphones at > 12 megapixels;
facial recognition, smile-detection etc. all gimmicks,
although the ISO-ranges which now extend up to 3200 is useful in low-light.
Stick with something robust and dust/moisture-proof.

Despite what the photography purists say, a useful feature is realtime LCD-display;
you would be surprised how often you try taking a photo
where you can't get your eye to the viewfinder (like above your head into a ceiling void).

Choice of flash should also be considered;
make sure it can communicate fully with your SLR's software
(i.e. often pretty much the ones recommended in their brand brochure)
and it's good to have one with an infrared-assisted auto-focus beam;
these units are often a bit taller for it, meaning they are easier get snagged,
but it is frustrating trying to take those dark interior shots without-.

The distinction between camera and camcorder is also blurring,
each pretty much capable of both video and stills,
the most obvious difference being the use of a flash;
some say the camcorder images are the better for it in reasonable low-light,
(less contrast and shadows) although obviously not in no-light;
I'd actually consider one as a backup-camera.

Some of the current crop of compacts come with built-in GPS and WiFi, allowing geotagging;
(or in the case of some cellphones with built-in compass and GPS,
for you to point it at a landmark, press the Wiki-app and upload tourist info...)

Soon the likes of Pat and John will be able to retire as armchair FI's;
sending out young FI-appi's armed with a WiFi camera and a shovel,
beaming back realtime footage to their cosy studies, scotch in hand;
"Excavate a bit to the left, open up that DB-cover, bag&tag that debris"