In the coming year I plan to paticipate in even more challenges (because, you know, procrastinating from drawing my own characters is better with an excuse :| ), among which are:
January: JanuHAREy. Maybe not all prompts, there are things I'd like to do besides drawings, but I definitely aim to do at last some.
February: FebROOary and Froguary seem nice, and would give me opportunity to learn how to draw kangaroos and frogs better.
March: March of Robots - I don't think I drew robots that much, so it's a perfect opportunity to catch up :) 5 Minute March - this one is interesting and easy at the same time: speed drawing with 5 minutes time limit (or 10 minutes, the purpose is to practice speed drawing and sketching).
April: Hmm, I haven't really find much themed challenges for April, but I'll either do some art for myself, or find soemthing to draw.
May MerMay and marine species. 8th - the LoliBear day.
June Junicorn - uuuunicorns! :) Copyist June Art Challenge - this one is interesting: redrw/replicate a sketch, drawing or painting by a master or from art book a day. I think it will be really helpful. Maybe this is what I'll be doing in April?
July ArtFight will be my main focus here, but there are also two other challenges I find interesting: Julycanthrophy - with were-creatures (not only werewolves), and Portrait July - with portraits. This one is easy to incorporate with the ArtFight :)
August I'm interested in participating in Smaugust. I definitely could use practice with drawing dragons. 15th - the Nimbat day
September Sneptember (snow leopards), Sketchtember (sketch-a-day, where the goal is to make quick sketches rather than finished illustrations; similar to 5 Minute March), Swordtember (various fantasy-looking swords) all seem nice.
October As each year, the Inktober will be my main focus here, but I'm also interested in doing OctoBear, especially since my avatar is a bear. Well, if not here, I'll do in later, in December (as DecemBear) :) Other worth noting challenges here include Orctober and Gobtober (orcs, goblins, etc.), Foxtober (foxes), OC-tober (original characters, which I have quite a lot by now), Kinktober and Goretober (nsfw, but I'm not sure about this one), and UndyingTalesProject (drawing animal and plant species near extinction). 20th - the LoliBat day.
November Huevember is nice for working with colors, Posevember helps with poses, Dinovember is dinosaurs... very nice!
December DecemBear, DecemBird, DnDcember, DigiCember (digimons, I presume, though I have not much experience with the show) And there's the Happy Nude Deer picture I do for the year's end + I think I'll make the Christmas Eve pinup a regular thing as well.
-- Of course, right now I have plenty of enthusiasm for it, but life is life, and I know I wil be doing other things too (I think it's time to finally start playing those games I bought and wanted to finish years ago...) plus runnning RPG game(s), plus there are regular life stuff (like work - takes 1/3rd of a whole day, unfortunately, which is more than I usually sleep), so with roughly 3-6 hours of spare time that needs to be divided between several options... well, I don't expect to do all the challenges listed above, but I will certainly try to do something for each