CSS attribute selectors
I wrote this post a while back. The content can still be relevant but the information I've linked to may no longer be available.
There are some relatively under-used CSS techniques and one of these is the use of attribute selectors. Attribute selectors allow you to define a style based on the presence or value of an attribute. For example, you can style external links differently to internal links using attribute selectors.
There's no reason not to use attribute selectors because browser support these days is pretty good - although the relatively slow uptake of Internet Explorer 7 may put you off.
Don't be afraid, there are some neat things that can be done with attribute selectors! And they are sure to become more widely used when the market share of Internet Explorer 6 decreases further.
Previously: CSS attribute selectors - clever styling