The Olympus lens lineup has two macro lenses: the 35mm and the 50mm. The 50mm ƒ/2 is listed in the ''High Quality'' lineup, developed for high performance in sharpness, brightness and close-up shooting capability. It's also listed as being dust and splash-proof, to allow usage in harsh conditions. Available for $425.
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 100mm. The lens takes 52mm filters, and comes with a bowl-style lens hood. Read the whole test here