(from jQuery in Action)
Basic CSS selectors
* - any element
E - elements with tag E
E F - elements with tag F that are descendants of E
E>F - elements with tag F that are direct children of E
E+F - elements F immediately preceded by sibling E
E~F - elements F preceded by any sibling E
E:has(F) - elements E that have at least one decedent with tag F
E.C - elements with class name C. omitting E is the same as *.C
E#I - elements E with id I. omitting E is the same as *#I
E[A] - elements with attribute A of any value
E[A=V] - elements with attribute A whose value is exactly V
E[A^=V] - elements with attribute A whose value begins with V
E[A$=V] - elements with attribute A whose value ends with V
E[A*=V] - elements with attribute A whose value contains V
Advanced positional selectors
:first - first match of the page
:last - last match of the page
:first-child - first child element
:last-child - last child element
:only-child - elements that have no siblings
:nth-child(n) - nth child element
:nth-child(even|odd) - even or odd children
:nth-child(Xn+Y) - nth child element computed by formula
:even and :odd - even and odd elements page wide
:eq(n) - the nth matching element
:gt(n) - elements after (and excluding) nth matching element
:lt(n) - elements before (and excluding) nth matching element
Custom selectors
:animated - elements that are under animated control
:button - any button
:checkbox - only check box elements
:checked - check boxes or radio buttons that are checked
:contains(foo) - elements containing text foo
:disabled - form elements that are disabled
:enabled - form elements that are enabled
:file - selects all file elements
:header - all elements h1..h6
:hidden - elements that are hidden
:image - form images
:input - form elements
:not(filter) - negates the specified filter
:parent - elements that have children
:password - password elements
:radio - radio elements
:reset - reset buttons
:selected - option elements that are selected
:submit - submit buttons
:text - text elements (input[type=text])
:visible - elements that are visible
