You may find Perl Catalyst and Cloud Computing interesting. However, I'm I agree with Your Mother that going efficiently, safely, robustly, maintainably won't be easy nor fast.

I'd start building something small and easy to change, so it grows as needed. Take a look at Getting Real by 37signals. It has a lot of tips on how to and not to build a web app.

Update: Rephrased me agreeing with Your Mother. Thanks Burak ;)