I have been looking for the equivalent of CommandT for buffers for a while, and the closest I've found is this: http://www.vim.org/scripts/script.php?script_id=1890
Unfortunately it's fuzzy file matcher is nowhere near as useful as CommandT's, so you'll have to use them in conjunction.
:help CommandT
...
*:CommandTBuffer*
|:CommandTBuffer|Brings up the Command-T buffer window.
This works exactly like the standard file window,
except that the selection is limited to files that
you already have open in buffers.
MAPPINGS *command-t-mappings*
By default Command-T comes with only two mappings:
<Leader>t bring up the Command-T file window
<Leader>b bring up the Command-T buffer window