Common to Windows and Mac fonts and the respective font family. Cross browser fonts.
Arial, sans-serif
Verdana, sans-serif
Trebuchet MS, sans-serif
Georgia, serif
Times New Roman, serif
Impact, sans-serif
Comic Sans MS, cursive
Courier New, monospace
Sans-serif renders as Arial if nothing other declared. So, if Arial needed, just say sans-serif!
Serif renders as Times New Roman if nothing other declared. If nothing declared, Times New Roman is displayed.
Just to say, bitmap fonts (none of above) are designed for 8, 10, 12, 14, 18 and 24 point sizes at 96 DPI.