That issue was just mentioned...
2. The list of fields to search on needs to be sorted...
...and/or broken into functional groups in a nested menu.
The issue exists, of course, wherever a field has to be chosen. It's much more of an issue now for those of us using a significant number of custom fields. Also, after using a custom skin for a time, the "logic" of the way the fields are presented in the default skin is of little help.
On second thought, I don't think the idea breaking them into functional groups is workable. Even if we could define groups that everyone would find intuitive, the only way to handle custom fields would be to put them into their own group. That would create more problems (e.g., for a secondary user who doesn't know which are standard and which are custom).
I think the best solution would be to use a common alphabetically-sorted picklist wherever a field needs to be chosen. Typing the first letter of the field name would jump to that place in the list—so a list presenting 10 or 20 fields in a window or drop-down would be workable. This would be a little less convenient for common simple searches (those that appear near the top of the current list), but many of those searches can be done by right-clicking on the displayed field anyway.
It would be slick if three or four MRU items appeared at the top the list. It would also be nice if standard, custom and file information fields could be filtered by way of check boxes at the top of the list. That would be handy in the common situation where I know the field type, but can't remember the name.