With services such as Google Fonts making it simple to add more flavoursome type to your web designs, there are few reasons not to consign the likes of Tahoma and Arial to the "if all else fails" bin. What is bothersome is having to change a font and reload a page just to see what it looks like. That's where TypeWonder can save you time.
TypeWonder taps into Google's supply of open source fonts and allows you to preview those fonts on any website you care to imagine. There's no fine-grained control -- it replaces everything with the selected font, so it only gives you a broad idea of how it meshes with the site.
This, however, is often good enough when you're after something to use for body text.
If using a website for this sort of thing is too old-school, TypeWonder also has a Chrome extension (sorry Firefox users, nothing for you at the moment).