I'am using NestedView plugin to have logical groups of jobs and it helps A LOT when you have 50+ jobs.
The functionality added in 6235 is nice but one thing may help too.
Add a BuildStatus icon for the nested jobs.
Something which show immediately that one nested job has not built instead of showing a Sun icon and a tool-tip "Average health is 81%"
Use of the same Color Code than classic BuildStatus icons would be great.
Maybe replace the current folder icon by a set of coloured ones.
This item is linked to http://issues.jenkins-ci.org/browse/JENKINS-6235