It seems that spell-checking in vim is normally enabled at a buffer level (
set spell vs.
set nospell). However, sometimes it would be useful to ignore certain parts of a buffer (for example, URLs in text files often contain "nonsense" from a dictionary perspective, but are nevertheless valid and correct).
Is it possible to use the spell-checking support in vim only for parts of a buffer? For example, can one define regexes to ignore? Alternatively, are there any third-party spellcheckers for vim which can do this?