LaTeX currently inserts ligatures automatically. There are however some words (at least in german, but I think the same is true of other languages) that should not get ligatures. An example is "Auflage", "fl" is usually converted into a ligature, but this is wrong. There is currently a perl-script out there (http://www.ctan.org/tex-archive/support/rmligs) that basically uses a dictionary of words that shouldn't get ligatures and inserts "| that breaks the ligature at the right place.
It would be nice to have an option below "spelling" like "ligature check" that searches through the document (and ideally, through the tex-files included via \input or \include) using the dictionary, asking the user if he wants to insert a ligature-break (kind of like the spelling-check). As far as I know this would be the first editor to have this feature.
Best regards and thanks for your hard work,