I picked up a copy of Baseball Prospectus 2004 the other day, and it's pretty darn good. A little less creative than it's been in past years, and the article on the Astros is a little dry (they basically slam our farm system and our signings of Viz / Ausmus....well, thanks), but it's still the most entertaining baseball analysis book there is. And I love baseball books, after all.
Speaking of baseball books, there's a new one coming out soon (April 27, to be exact): The Bad Guys Won, by Jeff Pearlman. It's a biography of the '86 Mets, who beat the Astros in an unbelievable playoff series. The book spends a lot of time on the '86 Astros, too, especially Mike Scott, who was the Series MVP (on the losing team!). There are tons of interviews, stats, trivia...don't take my word for it. Check it out.