Droptext gives you read/write access for any plain text files on your Dropbox account. You can edit, delete, and even create them from within Droptext. Unfortunately the app has been pretty buggy for me. I am unable to open any file that isn’t a test file, and the app crashes often. But it’s a great concept, and I really hope Droptext sees some refining and polishing in the near future. (Via Nathan.)
Also: it absolutely boggles my mind why Dropbox doesn’t have this functionality built into their iPhone and iPad apps.