Having managed a book store, I have to disagree with you Ookla (I know, it rarely happens). This is actually the BEST place for a thread of this SPECIFIC nature.
People like to know what authors will appeal to them after having read a certain author. I DO think, however, that while posting on this thread, you need to make certain that you are posting "If you like Sanderson, you will like (insert author here) BECAUSE (insert reason here)."
What I mean is, simply saying what you are reading doesn't actually fit in with the OP's question. People want to know what they should read BECAUSE they enjoy Sanderson. Does that distinction make sense? If you are just posting what you like, they by all means, get the heck out. However, if you are posting reasons why people may like, say, Rothfuss because you see similar themes or writing techniques, then that is fine.
Please remember, a lot of book sales are done through recommendation. But, it has to be done intelligently - not just a list of what you think is neat.
For example, I would never recommend Brooks, Eddings, or Paolini (read: rip-off of the prior mentioned authors and Star Wars) to people who read Sanderson if they are over the age of 14. They dont have the depth, technique, or intelligence to match Sanderson's novels.
In my experience, many people who read Sanderson's novels tend to gravitate towards the following (note: there are exceptions to all of these):
Guy Gavriel Kay - Something about the settings, and politics seem to strike similarities. In addition, he is an author that Brandon recommends.
Steven Erikson - He's not for everyone. But the people who like the intelligence and depth of Brandon's work, and who want even more, really dig this guy. He is my personal favorite. I actually sold more of his novels than i did of Brandon's (which says a hell of a lot). I think more Erikson readers will read Brandon's stuff after reading the 3rd MB novel.
George R R Martin - There will be an endless debate over this and the, uh, appropriateness of some of his writing. However, it was hard for me to ignore that readers tend to like both. I think more Martin readers will go for Brandon's stuff after reading the 3rd MB novel.
Patrick Rothfuss - They are friends. They like each other's work.
Scott Lynch - Locke Lamora is a great novel. The similarities begin with the heist theme that is introduced in Brandon's MB1. They diverge after that, but people like them both for the Heist theme. Beware of language in this book.
Abercrombie - All that you've heard is true. This guy is great. Really, he is a 2nd tier "if you like Brandon" book. The reason being that he is more of a variation on the grittiness and humor found in Martin and Lynch.
Those are a few people I recommend "If you like Sanderson's novels." There are more, but it all is very dependent on what you do and DON'T (very important - arguably more important than what you DO) like.
So, I, Not Bookstore Guy Anymore, approve of this thread.
As long as you do it my way. Because that is the correct way.
The End.