Trello’s sign up page.
Lovely and simple - no extra help needed here, because the fields are so standard. The placeholder text gives you a hint if you need it.
What makes it special? That placeholder text. Among others, you can get Ender Wiggin (ender@battle.edu), Hermione Granger (hg@spew.org.uk), and Arya Stark (needle@mail.wi.wes). It’s a nice touch. Doesn’t get in the way, and doesn’t stop the placeholder text being useful, but if you get the references, it adds that little something extra.
The only thing that’s a shame is the error messages aren’t so smooth:
The error isn’t next to the field, and it’s not particularly nice (the name field was empty, so they could easily have given a smarter message). It’s a little robotic too.
It’s worse if you enter a password that’s too short: the message you get is “Invalid password”. There’s no guidance about what makes a valid password, which makes it hard to work out what’s wrong.