Curlybird:
Better to have it and not need it than need it and not have it - you just never know 
I battle with this sometimes..... I would trade good photos of common-uncommon birds for a good look at a lifer. I often notice that when I accidentally forget my camera, great photo ops arise. But, if I purposely 'forget' my camera, it is like fooling with karma and I wind up seeing nothing worth while.... for binocs or camera.
I try to bring it as often as possible though. The 'just having it' theory allowed me photos of a true albino and true melanistic gray squirrels (in the same month, same park) and a leucistic House sparrow that had an entirely bleached blonde head. I've noticed that when I do have my camera, I am looking at things in more of an artistic way.... trying to frame a bird, capture sunbeams coming through a landscape, to try and portray to a viewer what I felt and saw when taking said photo. For me, this also allows/helps me remember other aspects about that photo, that individual spot, the whole trip.... whatever. (see ramblings below)
That theory gave me one of my favorite photos to date..... I was hiking in Chugach National Forest (camped 3 days/2 nights), about an hours drive north of Anchorage in Alaska, and I wandered upon this guys territory. Beforehand, I took some photos of just the spruce cones because they looked neat in a photo the way the needles contrast with the cones.... so I already had the camera around my neck (another battle....when to have the camera out with the binocs, just binocs, just camrea....). Red squirrels give the absolute best chatter!

This area was several hundred mountainous acres of dense spruce, thickets of willow and alder, some open rock ledges (lots of sheep), and beautiful streams/rivers running through everywhere..... I was there in September so creatures were busy filing up for a long flight, or long winter. Tons of red squirrels, Boreal and black-capped chickadees, Tree/Fox/Golden and White-crowned sparrows, both crossbills, redpolls, siskins, Gray jays, Downy and Three-toed woodpeckers (missed Hairy there, got him further south.....missed Black-backed, got him further north), unexpected Dippers in an crystal brook, Juncos, Kinglets all over, Varied/Hermit and Swainson's thrush (missed Grey-cheeked!!!), Orange-crowned/Wilson's/Yellow and yellow-rumped warblers, N waterthrush, and Pine grosbeaks, moose, sheep, bear, ravens, both eagles, merlin, goshawk, Harlan's red-tail and Rough-legged hawks, The only obvious misses I had during that 3 days span were GC rosy-finches and Grey-cheeked thrush. I was in all elevations and habitats..... camera was out most of the time! (that is until the battery died the morning of the 3rd day)
(most of that was from memory.....had to bust out the old notebook for some.....)
Life List: 302
Recent Lifers:
November:
Vesper Sparrow
Black Scotor
Surf Scotor
October:
Hudsonian Godwit