5 CSS properties you probably never use or might use.
clip
clip: rect(5px, 40px, 45px, 5px)
From iBloom Studios
A good way to visualize the clip attribute is if you take a piece of paper with a rectangle cut out of it and place it on top of a photo (just like using a photoshop layer mask).
The area of the rectangle hole, allowing the layer behind it to show through, is what the clip property will specify.
They've got a lengthy article all about the clip property and some examples of it in use.
text-shadow
text-shadow: color, x-coordinate, y-coordinate, blur-radius;
From Quirksmode:
The text-shadow declaration allows you to create a text-shadow: i.e. a slightly moved, slightly blurred copy of a text.
quotes
From htmldog
[quotes] specify what form the quotes of the open-quote and close-quote values of the content property should take. Not supported by IE.
A List Apart endorses the revival of the tag using content.
marks
From quackit.com
The CSS marks property is used to set crop marks and cross marks on paged media. This is used with the page rule.
empty-cells
Quirksmode has a great explanation of empty-cells in Fun with Tables: which shows a side-by-side comparison of a bunch of CSS table properties and which browsers they are supported in.