How about a line sorter ...
Given a set of lines or records, say tab delimited, sort the selected or all buffer lines based on at least the first field. Optionaly, sort on other fields. Better yet, sort on multiple criteria...

Something like this would be really sexy for some of what I do regularily. I can imagine it being handy for people who work with log files, CSV imports, 3rd party software imports and output, etc.