There are rules and regulations and laws getting mature on this issue. During these recent three or four years, the government has tried different VISA procedures.

Now it seems the rules are settled. The main source and the only source that I recommend to consider and stick with it is the UAEInteract web portal which is one of official UAE government portal that you can trust.

Find information for UAE VISA here: http://www.uaeinteract.com/travel/visas.asp