I love the Opteka 10X HD diopter. I use it with my 18 - 55 kit lens on my Nikon D60. I take it everywhere I go.
I also use a 60mm micro nikkor, and it is excellent. I've used the 105mm before, which can get a little closer than the 60, but it's about double the price.
If you want an excellent macro lens, go with the 60mm. But if you just want to spend $30 to play around with macro at home, get this:
http://www.amazon.com/Opteka-Profes...1?ie=UTF8&s=electronics&qid=1252375413&sr=8-1
Some pics I took with my Opteka HD 10X macro diopter (the "large" size shows more detail):
<a href="http://www.flickr.com/photos/feliciamccaulley/3654997734/" title="Duncan and snail by Felicia McCaulley, on Flickr"><img src="http://farm4.static.flickr.com/3402/3654997734_313e7b852c.jpg" width="500" height="292" alt="Duncan and snail" /></a>
<a href="http://www.flickr.com/photos/feliciamccaulley/3673120677/" title="pom pom crab with eggs by Felicia McCaulley, on Flickr"><img src="http://farm3.static.flickr.com/2555/3673120677_6d82c6031d.jpg" width="500" height="427" alt="pom pom crab with eggs" /></a>
<a href="http://www.flickr.com/photos/feliciamccaulley/3725516476/" title="Pink Zoas by Felicia McCaulley, on Flickr"><img src="http://farm3.static.flickr.com/2511/3725516476_56b6631449.jpg" width="500" height="361" alt="Pink Zoas" /></a>
http://www.flickr.com/photos/feliciamccaulley/sets/72157621218388897/