Usability - Sign Up Vs. Register now
This is my observation, thoughts about the geological or say, social language usage, that is partly a usability issue in that particular context.
Some of the websites requires the users to “Sign in” with their user name and password. One can see a sign-in portion of the screen with the heading “Sign in”. Here, the word “Sign in” is interpreted successfully as the action, where one needs to provide/type their assigned user name and password to gain access. Since everyone has signed some documents, signed some entry books at doors to gain access.. the word “Sign in” makes good sense of the context.
Next, if you want to sign-in, you need to be a member first. To become a member, most websites allows the users to register or sign-up. I believe the word “Register” is more appropriate for use in India rather than “Sign-up”. Because in India, the word Register is used right from the school days onwards. You have the “Attendance register”, “Office Registers”, “Vehicle Registration”, “Registration at events” etc etc. So naturally almost every educated Indians are familiar with the word “Register” associating the action to : the act that enrolls or adds some object or object’s name to a list or group.
But Sign-Up may be relatively new (for a novice indian). Though it means the same meaning of “Registration”, a common man may take some time to understand or even guess what does that word actually means. Sometimes he may confuse it with Sign-in’s opposite! This, somehow falls close to an usability issue.There is only a 50:50 chance that a novice indian user can understand the meaning of Sign-up within the first two seconds. So I think, websites who’s targets starts with novice indians could use the word “Register” instead of “Sign up”.
The same story goes with the words “Browsing” and “Surfing”. Surfing is the americanized style , where as Browsing is desi style. I see a lot of people talking “I visited that browsing center”, “I just came from browsing center”.. and even the internet cafe’s are mostly named as ” Internet Browsing center or Internet Cafe or Cyber Cafe” etc. Rarely I see some ” Internet Surfing Center”. 
Disclaimer : The above is my thought. I do not have any documented proof. If you disagree or wish to add more, let me know.