Catastrophic failure of hard drive

I recently suffered from a hard drive failure that erased 2 weeks of data.
In order to prevent this from happening again, I've decided to move as many files and activities as possible online. This means using a number of web sites to complete work I would normally do on my computer.
Why do this, you ask?
Well, I now have a HTC Diamond so I can complete tasks while on the road. There are also a large number of sites that will integrate nicely with SMS reminders.
I'll compile a working list of site I'm using here.
In order to reduce the time installing software on new computers I'll also list software I consider essential and where to get them.

What software do you need to have and why?