While painting textures onto a terrain I was working on I managed to accidentally click and drag something in the project window onto another item, Unity gave me the pin-wheel and crashed, now whenever I try to open Unity the icon bounces twice in the dock and then crashes, is there anyway I can back into the software?
You can try to rename your project (like "_Project") so unity is unable to find it, so it will show "unity - project wizard" window.
You can show the Project wizzard window by holding the Option key (alt) while starting Unity.