Are you looking for free synths or patches for violin sounds? Or are you willing to/want to spend money? I think that Nexus might have some violin patches, but I'm not too sure about other synths. FM synthesizers like Sytrus are pretty versatile, so I'm sure that you could probably get some string sounds out of Sytrus. I don't think you'd be able to do that with Massive, not without putting in a ton of plugins, but Pewter Robot did make a thread in the "Sharing is Magic" forum where he posted some Massive presets he made of some string sounding synths that just need some work...
If you want to buy or pay money for some violin synths, I'd go with EastWest Symphonic Orchestra. It has some of the best violin samples you'll ever need (as well as every other instrument ever
) but that's pretty expensive (up to $400+). Or if you own Kontakt, you could find some string libraries...