Help/Cues: Gmail doesn’t say “you’re wrong” it says you have changed that password a while ago (exact time). Might give you the necessary ideas. 

I think I’ve seen this on Littlebigdetails before.

Showcase features: One of the greatest facts of Gmail is the indefinitely growing space for your email. On the sign up space they’re showcasing that fact in real time. Oldie but goodie.

Launch timing: Google’s Gmail launched on an April 1st in 2004. Many people couldn’t believe the features and thus creating even more spread (not that Google had problems with popularity at that time).

Do clever stuff: Mailplane (@Mailplane) alerts you when you said “I’m attaching” and you have actually not attached anything (I’m not sure if it’s coming from Gmail or from the actual app itself at this point).