I think Coda's clips are somewhat a clone of TextMate's snippets; and there are a bunch of clones of
that on
vim.org; try
snipMate, or
SuperTab continued, or
snippetsEmu. For HTML/CSS-specific coding, there's
ZenCoding, which is quite popular.
As far as colors go, I use MacVim's default, with a few minor tweaks and the background color set to LemonChiffon3 (sort of a light tan, much easier on the eyes than pure white).
Note that Vim offers several levels of color support: all the way from only-inverse/bold/underline on an old-school terminal, through support for color terminals (with 16, 88, or 256 colors available), to full-blown GUI environments (with full 24-bit color, 16 million shades available).
Many Vim color schemes only support the latter (24bit color), while Terminal.app only supports 16 colors (and then only with some unusable shades; if you want to use anything that shows colors in Terminal.app, you
really need to install
TerminalColours, probably the version
patched for Snow Leopard, and tweak the colors to be more usable).
So most of the more elaborate "theme"-oriented color schemes aren't going to work in Terminal.app no matter what. If you want your Vim windows to look
just so, then use
MacVim (highly recommended in any case, and go for the
latest snapshot which is
years newer than the "featured download", and just as stable if not more so).
If you want other good ideas for plugins or color schemes, browse Vim.org's scripts archive sorted by
highest rated or most downloads.