Welcome to work|i|o the one stop shop for...blah.

Or some form of one line and clear explanation of what the site is/does.

You're trying to get across 3 things very quickly here:

1. What the site is for. 2. How does it work (how can I use it?) 3. Why should I use it (what's the benefit for me?)

If there are alternatives, why should I use you instead of the alternatives? (e.g. too expensive, too clumsy, too rancid or whatever).