This relates to data.gov in a tangential fashion - however perhaps either the data or the dashboard could reside within Data.gov:
The idea here, toward government transparency, is to develop a simple, common format for reporting FOIA requests, with a historic and status context, e.g. number of new requests opened in a given month, number of existing closed in a given month, number of requests outstanding broken out by number of months, and so on.
A simple XML, CSV or other basic flat-file format could probably accomodate this. Similarly, a basic, agency-customizable reporting tool could be developed and disseminated to all agencies.
These could then be collected centrally by Data.gov or some other Federal site (e.g. OMB), and be presented using simple web-based graphical and textual reporting tools.
Essentially, the notion here is that FOIA requests and agency data publishing and sharing are related functions. Agency data publishing can reduce FOIA request loads, and this can provide metrics for assessing progress and transparency.