Thanks for the emails on my Year's Best three-for-three with "Lesser Demons." So far the only horror 3-fer a reader has identified is my buddy Laird Barron's "Proboscis," which made it into two horror Year's Bests and one for fantasy. So, not quite a strictly horror 3-fer... but, hey, always great to be shoulder-to-shoulder with Laird, and "Proboscis" is an outstanding piece of work.
Also, editors Ellen Datlow and Paula Guran emailed with a little history of horror's Best ofs. Here's a chunk from Paula's email (i.e. ring the bell, school's in, sucka):
"Prime did a Horror: The Best of the Year: 2006 (Wallace & Betancourt) and for 2007; Stefan Dziemianowicz was supposed to do 2008, but that didn't ever get published. So there were two years that there were three.
"Otherwise: Year’s Best Horror Stories was done by Gerald W. Page from 1976 to 1979, and Karl Edward Wagner from 1980 to 1994. Ellen's (and Terri & then Gavin & Kelly) Year's Best Fantasy and Horror ran 1988-2008, then her Best Horror of the Year started 2009, so this year is her third. Stephen Jones's Mammoth Book of Best New Horror started 1990 (with Ramsey co-editing first six). SO -- there were at least three or four years those three overlapped.
"Yeah, as Ellen said I think there have been stories that went threesies--maybe more... if you count year's best sf and/or f compilations. Of course I don't consider mine "horror"... it really is dark fantasy, but since I include non-supernatural stuff "horror" is in the title, too. Right now Strahan does The Best Science Fiction and Fantasy; Rich Horton does The Year's Best Science Fiction and Fantasy and, of course, Gardner is still King o' the YBSF. Hartwell & Cramer still do Year's Best SF, and I think they still do YB Fantasy."
Of course, I like Paula's other comment best -- "However you look at it, you are singular." Which I guess puts the rubber stamp to the whole deal (i.e. you can't argue with a lady who's right; not even a little bit).