Another field that's painful for the same reason is the store field in the advanced search.
Now we've upgraded these fields with a different widget which allows scrolling OR searching. Searching is a much easier way to quickly narrow the long list to a few items of interest (such as all the "carpet" categories).
A second change now possible due to this interface improvement is that we've added ALL the subcategories to the search field where it was previously just the short list of top level categories.
There are a lot more usability improvements opportunities, but we hope you feel the immediate impact of these updates!