Carbonite announced the availability of a Mac version of its online backup service that works with Intel-based Mac systems running OS 10.4 or 10.5. Carbonite places a lot of emphasis on ease of use and security, with encryption occurring before, during, and after the transfer to online servers. It also has the ability to encrypt files using a key that only the user knows, although Carbonite doesn't recommend this option, as company staff will be unable to recover any data if the user loses the key. Carbonite charges $54.95 a year. Mozy also has a Mac client which offers up to 2GB of storage space for free, or unlimited storage for $4.95 per month (or $59.40 per year).
More info: Carbonite for Mac