Create a Custom View for Constituent records or for a particular Event and be able to enter/change data within the Custom View without having to flip through different tabs. Have fields you choose from different tabs within a constituent record or an Event/Participant Record on the same screen and be able to add/change data for those fields. This would speed data entry.
Becareful what you title your ideas. They already have Custom Views - they are just that, Views. You can not edit data. I agree that I want to be able to customize screens - but I think you can already do this if you pay big $ for the API and even more for a programmer. I hate to say it but I would not hold your breath for this.