On her blog, Tiffany Brown has a review of an online editing resource she came across that can help you write code and work with remote files via a web interface - WorkSpace (including HTML, JavaScript, CSS, PHP, SQL, Java, and Perl documents).

WorkSpace - which currently is currently in limited beta testing - is an online text editing environment with an eye towards web development. You can create documents and save them in your hosted sandbox, or directly to your server via FTP.

She talks about her experiences with it - both the good and the bad. She liked the simplicity of it all but thought it lacked a few of the features it needed. She also mentions the lack of version control in the application.

I do like the idea behind WorkSpace. [...] The downside is that you're trusting a company with all of your web site data. I'm not sure the slight gain in the ability to work remotely is worth the trade-off of giving WorkSpace server access.