Is there a webwallet for Monero? What is MyMonero?

MyMonero.com is much easier to use than the command line utilities and is ran by fluffypony, a Monero Core Team Member. I doesn't require registration or email (the first time, you generate a private login key and the next time you just enter it). A notable community member said: "It's probably the most intuitive UI I've used in my life (no kidding)."

You can mine directly to your MyMonero address. MyMonero is completely free to use and most of its code will eventually be open-sourced. Most of the work is done client-side, so MyMonero only has write access to your funds when you are logged in (and it logs out automatically pretty quickly so you run no risk of accidentally letting your wallet open). Finally, MyMonero is compatible with openalias (so you can donate to the dev fund  just by sending to donate.monero.cc) and uses HSTS.

In the future, you will be able to take advantage of the viewkey mechanism (read-only access for selected third-parties) as well as use it as an alternative access point for your regular wallet.