Like many others, my emergency fund is basically a job loss fund, too. I keep about 5 months of expenses in it. About a year and a half ago I went through three months of unemployment which was pretty grueling, and got another job just in time to avoid scraping the dregs on my accounts. Scary stuff. Five months gives me much more confidence, and my skills are greatly improved now, but my situation is still single-income, which is always a bit riskier.
Although, to be fair, I also like to keep about 3k in a car account and have an HSA (not yet invested) that could cover my deductible two times over. I do like my security, but I committed to one number for the emergency fund and am sticking to it. It would be too easy to keep dumping money into that account out of fear, so I've determined that any excess will be used for non tax-sheltered investments or saving up to buy into non tax-sheltered investments.
Honestly, I think those three categories pretty much cover anything you might need: job loss, car problems, and medical costs. I guess if I were a homeowner, I might have a stash dedicated to housing expenses, too. I prefer categories over one giant bucket :)