While surfing the web I sometimes think that people don't really know or use the <label> tag in XHTML.
Obviously, <label> isn't well known and it's usefulness is limited. But whenever I have to click a combo-button directly I remind myself to not forget that label next time I do something similar!
Here an example:
Option1Option2Try selecting Option2 by clicking on it's text instead of trying to give a headshot to that small bullet in front of it :).
And here labels come in. By using <label for="<ElementId>">Text</label> you can link the control (Everything, Textboxes, Checkboxes etc) to your description text.
Obviously this als helps search engines to not mix up Form data with real content on your page!