How to display member's username?

I'm building a php block using Deano's tools, and I have a form I would like the Member's username prefilled in the form, is there a way I can do this? It's a signup form for an adult networking site (good conversions too), and it would be much easier if their member name was already in the username field. I know one of you wiz's can do this. Thanks in advance!

echo getNickName();

Thanks Deano!