vim/runtime/autoload

The autoload directory is for standard Vim autoload scripts.

These are functions used by plugins and for general use.  They will be loaded
automatically when the function is invoked.  See ":help autoload".

gzip.vim	for editing compressed files
netrw*.vim	browsing (remote) directories and editing remote files
tar.vim		browsing tar files
zip.vim		browsing zip files
paste.vim	common code for mswin.vim, menu.vim and macmap.vim
spellfile.vim	downloading of a missing spell file

Omni completion files:
ccomplete.vim		C
csscomplete.vim		HTML / CSS
htmlcomplete.vim	HTML
javascriptcomplete.vim  Javascript
phpcomplete.vim		PHP
pythoncomplete.vim	Python
rubycomplete.vim	Ruby
syntaxcomplete.vim	from syntax highlighting
xmlcomplete.vim		XML (uses files in the xml directory)