Amongst non-Macro lenses, the Voigtlanders are good, the Lumix 7-14, and also the Sigma 18-35... minimum focus on that is listed at 11" (~27cm); it has a nearly identical max reproduction ratio as the Voigtlanders.
Natively, the Oly 60 macro, PanaLeica 45/2.8, and the older 4/3 Oly 50/2 and 35/3.5 are all very good as well.
i got the voigtlander 25mm off ebay in great shape for $550, i was extremely surprised how close you could focus with this lens, didnt even think about that when i bought it but you can get super close and super shallow depth of field.