as the year winds down, people seem to like to produce their "best of" lists for the year. the bad astronomer, phil plait, has produced a beautiful list of his top ten astronomy pictures of 2007, complete with informative explanations about what youre seeing! check it out!
i'll add a favorite picture of mine from this year.... comet mcnaught over patagonia in south america, showing the disk of our milky way galaxy in addition to the two strange galaxies: the large and small magellanic clouds! (see full explanation here)