As all-purpose lenses go, the 14-42mm ƒ/3.5-5.6 is a good example: light, fast-focusing, with a respectable maximum aperture and zoom range. It comes standard with the E-410 and E-510 kit packages, but could also be purchased on its own for around $250.
Since Olympus digital SLR cameras employ the four-thirds imaging sensor, any lens attached to the body will have an effective focal length (in 35mm terms) of double the listed length. Thus, for this particular lens, it will exhibit an effective focal length of 28-84mm. The lens takes 58mm filters, and comes with a petal-shaped lens hood. Read the whole review here