I’ve seen a couple of churches recently call for them for the month of January. I’ve been asked 5 or 6 times in the past year the whys and hows of fasting. Here’s a great reference from Bill Bright about fasting.
Another great reference is a book called Celebration of Discipline by Foster. It’s a tough read, but it’s worth it. It’s all about the freedom found in living a disciplined life rather than approaching it from a legalistic point of view.