I love my Pentax K-7. It's a tough, reliable DSLR that is feature rich and intuitive to use, the perfect combination for me. Now Pentax have released it's successor, the K-5, which is in many ways an evolution of a very successful camera body. An excellent review with a side-by-side comparison of the K-5's improvements over the K-7 has been published on the Pentax Forums here:
After having my K-7 pounding by snow in a blizzard two thousand metres up in the Austrian Alps last Christmas, and still keep shooting despite being soaked and half frozen, I can heartily recommend the build quality of these excellent new DSLRs from Pentax.
Updated 2022 : note that the above post was originally published in 2010, but is left here for archival purposes.