I say concerti almost all of the time too..
But hang on, those are different. Isn't because they are Italian words and Italian plural forms? Isn't "i" the italian plural of "o"?
I don't know, though I should. I am sure Italian speaking forum members will know.
Personally I like concerti, staccati and pizzicati. But then that's the Italian in me I suppose...
Yeah.. that is effectively why fungus (can) pluralize to fungi, because it is originally a Latin word.
Incidentally, I've seen it argued that the correct plural of octopus is in fact octopodes, because octopus is originally derived from Greek, NOT Latin (compare 'Oedipus') and in Greek -us pluralizes to -odes (and -is to -ides, making the theoretical plural of clitoris clitorides, believe it or not). Of course I don't think anyone is likely to use these plural forms.
I once had an enormous (amusing, but completely pointless) argument with a girlfriend (a language teacher, incidentally

) over plurals. It all started over stadium: stadia or stadiums and ended up comically with her shouting singulars at me and me trying to return the "theoretically correct" plural eg cherub cherubim; apparatchik apparatchiki;court-martial courts-martial; blintz blini.
I have to say I still don't like stadiums, but what really pains me is when someone uses "datas". Data is already a plural..