As a result of a Digital Photo magazine offer, I bought a set of lenses that attach to my Canon 24-105. I have toyed with the idea of buying a macro lens, but they are pretty expensive, and I don't know I would get the value, as I am not into nature photography and the like. But I like macro and it produces some nice abstract images.
You screw what looks like a circular filter over the front of the lens after taking off the UV filter. I have not quite mastered it yet, and the set comes with lenses that go from +1 dioptre to +10 dioptre, and when they fit, you can screw them on in stacks. This set set me back about £20 after discount. I meant to take a not of what I used for each shot, but it doe not really matter at this stage. Take a look at this, shot on manual focus, hi f number, hi ISO (because it was hand held and shot indoors). I call this 'fading flower'. I plan to unearth my tripod and take it out into the garden to see what else I can do. There were no instructions with the set as I found it, so it will be a matter of trial and error. Good fun.
Obvious things to note are narrow depth of field despite hi f number and very out of focus background (nice). I captured this in RAW, which is all I use on my SLR at the moment, and tweaked the RAW file sharpening it a little and reducing the noise. I also upped the colour temperature to be a bit more like daylight.