What is the best way to spellcheck in gVim? Is there an add-on or something? I would like it to offer corrections as well.
Use :set spell to turn on spell-checking. If it's source code, gvim is smart enough to only spellcheck comments and string literals.
:help spell will give you all the details. Here are some excerpts:
To search for the next misspelled word:
]s Move to next misspelled word after the cursor.
A count before the command can be used to repeat.
'wrapscan' applies.
[s Like "]s" but search backwards, find the misspelled
word before the cursor.
Finding suggestions for bad words:
z= For the word under/after the cursor, suggest correctly
spelled words.
To add words to your own word list: zg Add word under the cursor as a good word
Also see :help set spelllang for information on changing your dictionary to include other regions, languages, or word sets (for example, medical jargon).
gvim must be compiled with |+syntax|.
I don't put :set spell in my .vimrc because when I'm coding there are just too many variable names in my comments that get flagged. If there is a certain file type you want checked use an autocommand in your .vimrc. Or just turn it on manually when you need it.