Introduction to Information Retrieval (pdf/html)
nlp.stanford.edu
nlp.stanford.edu
I liked intro to IR better for almost everything else. For the size of MIR, the coverage of things like LSI, Clustering and Probabilistic Models seemed shallow in comparison.
Thanks, that's enough to make me want to read it :)
I think perhaps the word "Introduction" in the title is a little misleading because the book has good coverage and depth - recommended. Nice that they have it free online.