Is there any standard that has a list of web-safe fonts

W3C doesn't have a standard list simply because they aren't the ones who determine what fonts are installed on what computers.

Some of the most common fonts installed on most computers today include Arial, Verdana, Georgia and Times New Roman. There's no standard here, it just so happens that these fonts are included in most OS installations.

Font stacks are one way, the other way is to just use the ones that are common across Windows/Macinitosh/Linux - http://www.apaddedcell.com/web-fonts/.

There aren't really any "web-safe" fonts.

Standards do not require of browsers to always support specific fonts. It all comes down to what is installed in a specific OS. If a browser finds the specified font, it takes it. If not, it looks for a substitute.

The smartest option is to specify a list of fonts like this:

font-family: Arial, Helvetica, Sans-Serif;

If you are able to, check how your page looks with all of those in different OSes. That's the best performance you could give. Otherwise, develop your pages to be robust to some font size variations, that's always the best bet.