If you're not a fan of the ruby-on-rails / swiss army knife approach that IHP takes, check out Scotty. Add Lucid for Html rendering, and Selda for Postgres. (There are other options for any of these tools if you prefer)
hmm, last time I used Scotty, I thought it was the exact opposite of Rails and more like Sinatra. It's less batteries included and more flexible and lightweight. Yesod is more like RoR, no? Maybe I'm misunderstanding what you mean by swiss army knife?