It’s typically a good idea to have your updated resume handy. You never really know what may come up where you’ll need it. Having an electronic one (say, on LinkedIn) is good. Having one ready to print too would be best.
Creddle lets you create and maintain yours for free. You can choose from a number of templates (keep it as simple as you can, I say); its data fields are helpful in guiding you with what info you’ll want to include. When you’re done, you can export it to standard file formats, and even publish it to an unlisted URL for sharing electronically. And as far as I can see, it’s 100% free. I’ll update this if I learn otherwise.