In the list of historical builds (/build/viewBuildHistory), it would be great if the agent which a build ran on was a column in the table. This would let you visually correlate build times, successes and failures against particular agents which are misbehaving.
For example, we have the occasional slow build which runs for 30% longer than the others. See the attached screenshot. If we could tell that these slower builds were always on agent X, we could investigate the situation on that agent to try to rectify it.