While it's hard to get excited about an extra step in web planning, I think creating personas is a really important one.

Most sites are built by a team of people, all of different ages, gender, socio-economic backgrounds, religious beliefs and ethnicities. It can become easy when working independently of the team to infuse your own beliefs and biases into the work you're creating. Having personas helps keep these in check by staying focused on your site's authentic intended user.