If you haven't already, I highly recommend popping over to Dean Wesley Smith's blog and reading about his recent trials and travails with being executor for his friend Bill's estate. You might notice a certain someone was kinda active in the comments. I have dealt with aspects of probate often, and it's pretty rare for me to get a chance to warn people where they might actually listen. That aside, Dean's story is also a very touching tale of a deep and lasting friendship, and worth reading even without the cautionary aspect.
But please don't ignore the cautionary aspect. Even if you aren't a writer, you need to have a will. And do it right. Please. Please please please.