I've been looking at the del.icio.us auto text grow functionality recently, and noticed you can achieve a similar effect in CSS, but only for IE.
I originally thought this was a bug since it didn't work in Firefox or Safari.
The following CSS in IE causes any input element to grow to the max width of it's contents.
input { overflow: visible; }
The effect is that text input boxes automatically growth to the size of the content that you enter mirroring the functionality seen in the tag search on del.icio.us.
However, the question is whether (and I've not read the w3.org specs in detail) the 'width' CSS attribute should stop this from working, and whether it should work in Firefox and Safari.
My feeling was that IE was incorrectly making use of this CSS, but what do you think?