Deviltronics - Google Analytics can do it because I recently modified a load of keywords based on what people were actaully typing in. For example one keyword was 'face mask' in a safetywear campaign but some traffic was actually coming from 'buzzlightyear face mask' - not very obvious but it's now a negative keyword.
Dot, could you tell me how you are actually doing this as I can't seem to figure it out.