Countless times I've found solutions on the net: I'll try to give back some, by sharing interesting things I'll come across.
The most important field of web forms
How many times, while registering on some web site, you had to enter your email address twice?
What's the point? It's not a password and the field is not masked, so you can see if you typed it wrong.
Anyway, I always do a copy/paste from the first field. I guess many others do the same, thus obviating the whole check.
Even XKCD agrees...