Is your website about spreading libelous rumors about rich people / corporations? Are you putting up a webstore selling toys / food from China?

Seriously, IANAL, but lots of (unincorporated) websites collect email addresses (right down to everyone's personal blogs). Lots of businesses operate as sole proprietorships without problems... I may be stupid, but I don't think limited liability protection for a startup is (usually) very important. At least not in the early days.