Macro lenses are lenses that are designed for close-focus work, and can often reach 1:1 reproduction on their own. They tend to perform best up-close and at smaller apertures. As their name implies, they are designed for macro photography and are a terrific choice. They can also be used for non-macro work–they won’t have super-fast apertures (in the f/1-point-something range) but, most of the time, they’ll be very sharp when you’ve stopped them down.
The problem is that they can be very expensive depending on what you’re looking for. Modern macro lenses can easily approach $1,000, while even legacy lenses can still cost several hundred depending on the lens (and how long you’re willing to wait for a good deal to come around).
A word of caution: many older macro lenses actually achieve only 1:2 reproduction on their own and require the use of extension tubes to reach 1:1. If you want to shoot at higher shutter speeds, such lenses will require the use of a flash if you want to use the matching extension tubes to reach a 1:1 reproduction ratio. Another thing to consider is that a macro lens’s working distance at 1:1 might be too short for your needs.
Since they can be pricey, I cannot say it enough: do your homework and ask around before plunking down your hard earned cheese on a macro lens.