Please consider providing an API (or maybe extend existing plugin API) to be
able to show an aggregate view of all projects.

For example, this could allow to display a page (or generate XML representation
of) of coverage results (history?) for all (or wildcard subset of) projects.

The diskusage plugin already offers similar functionality linked
through "Manage Hudson" at:

http://localhost:8080/plugin/disk-usage/

Similar request was already made at:

https://hudson.dev.java.net/issues/show_bug.cgi?id=2775

for Static Code analysis plugin.