advertise isn't quite the exception that proves the rule -- just try to fathom the rule!

from alt.english.usage:
"-ize" vs "-ise"
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The following verbs are always spelled with "-ise": advertise, advise, arise, chastise, circumcise, comprise, compromise, demise, despise, devise, disguise, enterprise, excise, exercise, (dis/en)franchise, improvise, incise, merchandise, premise, reprise, revise, rise, supervise, surmise, surprise, televise. (At least, they're *almost* always spelled that way: "advertize", "merchandize", and "surprize" ARE listed in some U.S. college dictionaries, but are not the usual forms anywhere.) A useful mnemonic is that, except "improvise", none of these make nouns in "-isation", "-ization", or "-ism". (Exceptions in the other direction are "aggrandize", "capsize", "recognize", and verbs from
which no verb "-ization" has been formed because the parent or cognate noun already had the desired meaning.)

"Apprise" means "to inform"; "apprize" means "to appreciate". U.K. "prise open" = U.S. "pry open".

"Exorcize" is most commonly spelled "exorcise" in the U.S., though "exorcize" (which Fowler would have recommended) also occurs.

For other verbs, "-ize" is usual in the U.S. and recommended by Fowler, although "-ise" is also used in the U.K. Fowler recommends "-yse" in "analyse", "catalyse", and "paralyse", although "-yze" is usual in the U.S.


aaarrrrrggh