So I actually did wind up making a New Year's Resolution, which you can read about here.
My current yardlist of resident/visiting species is well over 300, which sounds really impressive but is less so than you might think. The impressive bit is that I actually got down on my hands and knees and looked for the darn things, and that's more a tribute to the weirdness of my hobbies. There is an extraordinary amount of life out there if you know where to look...and aren't actively trying to nuke it from orbit, of course.
In my perfect world (such as it is) we would all consider the number of species in our yards to be a source of inordinate pride. They'd give us property tax breaks for biodiversity. The perfect sterile lawn would be treated with mild contempt and HOAs would leave you faux-concerned notes stating that your grass was too short and appeared to be a monoculture. When you sold the house, your real estate listing would mention that there were spotted salamanders and ovenbirds breeding on the lot.
Oh well. Fantasy aside, the point is, I've knocked off a fair bit of the low-hanging fruit, and if I want to increase the count, I have to A) be lucky and B) actually get in there and look closely and track down IDs, not just throw my hands in the air and go "I dunno, it's a bee."
Fortunately for me, I got a surprise guest the other day, a lovely little blue-headed vireo attracted to the open water in the birdbath. This is an insect-eating species, although they'll nosh on fruit in the winter (I think the suet may have interested him a bit, and perhaps the rose hips.) This particular vireo's population is actually increasing, making them a rare good news story in the bird world. (Go, Team Vireo!)
So that's one down and forty-nine to go...