Interacting galaxies are neat. This group in Canes Venatici is especially noteworthy. NGC 4631 (the Whale) is heavily mottled and appears to be undergoing a great deal of activity. It is intereacting with NGC 4627 which has distorted it and the interaction is likely the source of the activity and a great deal of star formation. The smaller pair, NGC 4656 and 57 show even more evidence of interaction to my eye.
Details
Date and location - 2009-05-14 in backyard, Victoria BCCoditions - Clear, reduced transpareny, light wind, 7 deg C.
Equipment - WO 105 mm refractor with modified Canon 350D.
Exposure - 80 light, 20 dark and 20 flat frames for 80 min total exposure at ISO 1600.
Processing in Images Plus and Photoshop.