Samhain Publishing has open calls for two anthologies, each with interesting themes: Superhero Romance and 2012 Summer Olympics.
Some details from the editor for the as-yet-untitled Superhero Romance Anthology:
"I’m open to M/F, M/M, F/F, or multiples thereof, any sexual heat level, and the romance must end happily ever after or happy for now. The novellas must range between 25,000 to 30,000 words in length, no more, no less—please note, only manuscripts that fall in this word count will be considered for this anthology—and will be released individually as ebooks in spring 2012 and in print approximately one year later."
Deadline for this one is September 1, 2011.
As for the Summer Olympics 2012 Romance Anthology, the editor notes:
"I’m looking for stories that revolve around events happening during the Summer Olympics, being held in London in 2012 from July 27 to August 12. Stories focusing on the 2012 Summer Olympics in London are preferred, though a great story is a great story no matter the year and location, so I will be willing to look at stories taking place at/during previous Summer Olympic years and cities. Also, please be aware that, as a primarily romance publisher, we require all stories for this anthology to fit into the romance genre, complete with “happy ever after” or “happy for now” ending. Any heat level is admissible, as well as m/f, m/m, f/f and any ménage combination."
Same length (25,000 to 30,000 words) for this one, and the deadline is also September 1, 2011.
For more info on these anthos, check out the guidelines as well as Samhain's submissions FAQs page.