The only one its really nice to know is "dot dot" = I. It gives a quick check that you have identified an ILS while you check the chart or whatever for the full ident [which you should have done beforehand
]. The nice thing about Jeppesen en-route charts / approach plates is that they all have the ident written on them [can't speak for the other makes as I don't use them], so no in my opinion morse code is no longer nescessary. If you spend much time flying around a particular area you get to know the idents.
Cheers
EA