There’s a good article at Web Design From Scratch about using personas and scenarios to design a site.
I’ve found that personas and especially scenarios are a good way of grouping otherwise random requirements into a coherent story. If they can be boiled down to some concise ‘user needs’, then the design and functionality requirements can be clear for all involved.
In many ways, although this sounds like an ‘agile’ approach, it mirrors waterfall very closely. By creating these personas and scenarios, you can generate business rules, to which all requirements (both high level and detailed) mus trace themselves back to.
If you’re hell-bent on using agile, then the requirements can become user stories that Kanban processes can use (or whatever the developers prefer).
The Metlink site had some core user needs (scenarios) at its foundation. People wanted to know how to get somewhere, when it would leave, and how much it would cost. These three basic user needs became the foundation of the homepage design, allowing people to access this information as quickly as possible. The site is actually very simple, and people loved the way they could quickly get their timetables or journey information.
My only concern with personas is that people can become caught up in the edge cases that personas may imply. This is especially the case if you provide too much of a back story with each persona. Personas need to capture the core needs of the person in question and their scenarios, but not too much detail, otherwise you will over engineer the design for someone who doesn’t actually exist (a strawman).
Anyhoo, the Web Design from Scratch article has some good suggestions for discovering personas and how they can be used.