Add an option to change vehicle hotkeys. I have my headlights set on L, horn on H, but the server doesn't agree with me since the latest update (forces me to use H for headlights, which also triggers the horn since my settings are like that). I know that might be server-side mods/scripts but it should be a simple addition to just be able to change that key to whatever key you use for those.
As I see many players offer their businesses to be contacted via e-mail. It would be fun to see a webmail client (which you can log into only using your UCP name/password, then create mails for each character). So for example you can mail people outside of facebrowser for business communication.