1. Multiple selection everywhere it currently doesn't exist.
A killer for managing large projects as there's way too much ui clicking going on.
2. Ability to disable a build configuration
I have to do steps individually
3. Descriptions for anything with a title/name
4. Search field should work against object graph
Very painful to not be able to find references to parameters, etc. in graph.
5. Create a TeamCity DSL runner
I could create a form (say NewTeamCityProject) with prompts for values then inside TC build runner I could script against your DOM and easily add projects, vcs roots, etc.