I'd love to have a relatively easy way to hunt down and abort Harbormaster builds that aren't very useful, and perhaps to avoid some obviously wasteful builds. Examples:

1. Someone pushed several versions of a single differential, and it seems clear that only the most recent version is likely to be of interest.
2. A build for a different architecture/OS has failed for a reason that seems obviously non-platform-specific.
3. Only documentation files have changed. Building these on one platform should be sufficient.
4. A differential was closed by a commit. Only the most recent build will be useful, if that.

It would also be nice to get a list of build jobs waiting for specific platforms. These days, for example, we seem to have a lot more demand than supply for OSX bots. If we could get a list of all pending OSX builds, we could look through them by hand and see if any should be canceled.