Valediction in emails

In secondary school, we were taught that if we know the person, we use "Yours sincerely", and if we don't, we should use "Yours faithfully" at the end of a business letter.  Remember those rules?  


In any given work day, I find 30% of my hours consists of writing and responding to emails and so I slip into a routine of using the same finishing line in all my business related email correspondences.  Not that it matters that much what I put, I just don't think people care nowadays or would consciously read it. 

Recently though, I have been paying attention on how others choose to end their emails. 

They range from:

"thanks", 
"best regards", "Best Regards","BR",
"Regards", "rgds",
"cheers", 

to complex concoctions like:

"Thanks and best wishes" 

and...the most erupted way to end goes to "Best" - I guess that would be the internet-inspired, short for "Best Regards"?!

How do you end yours?  Enlighten me if you have any wicked ones you've come across.