You can register your business here in the US with the Secretary of State. Simply print out the form, fill it out, and send it back. I recommend registering a web hosting business as LLC for tax deprecation.
I am going to start new hosting site for US clients only. That is why I want to register my firm as LLC in US
Oh, for some reason I thought you wanted to register in UK & US. Check out LegalZoom. They can take care of your business registration, and it's quite affordable. I have used them for some of my projects and been happy with the result.