I do reckon that it would be rather inconsiderate of me to demand edges on a table without suggesting how it could be possible. There are 3 ways to do it, the last of which is probably the best:
Set an image as the background of a cell or cells.
Here's a hastily constructed (and not IE-ready) example of that on the right edge of this page:
One can also put the shading on the inside of the table by making a background that's the same width it is. I've done that on the center table of the Reference page.
A centered tiliing background as shown here.
There's a little CSS that makes the background tile center instead of tiling out from the left corner. It actually looks like this:
That's not IE-ready, but Parade magazine does the same thing.
I've known about this for a long time, but didn't use it on the site I made myself. Why didn't I do it? I don't know. In the future I may do it. No one will notice it, probably, but I will.