Based on Big John's Piefecta
This center col is first in the source, being a right float within a left-floated wrapper. The left col (second in source) is floated left in that same wrapper, and following the wrapper is the right floated right col (third in source.)
The headings and paragraphs are widthless and have 1px red borders to show any width problems in the columns.
Any column may be longest. All the columns are floated.
This is a test link.
This col is floated and also negatively margined to the left, so it is pulled out of its container except for a single pixel that is kept within the container.
This is here to make this column longer. This is a test link. This is here to make this column longer. This is a test link. This is here to make this column longer. This is here to make this column longer. This is here to make this column longer.
This column is floated, and then negatively margined to the right, pulling it nearly outside its container just like the left column.
This layout works in: IE5+/Win, Opera 6+, Mozilla, IE5/Mac, Safari.
bottom
Here is an "absolute" box, which stays at the col bottom.
AP. The side cols have bottom padding to avoid these boxes.