I have a web hosting business and am looking to be able to register client's domain names when they order a package from me. Is it legal for me to just use my account on godaddy and register them from there, or do I need a reseller package? If I need a reseller plan, what are some good cheap ones? I'm looking at www.10-domains.com 's. Any comments? Thanks!

im not sure about registering the domains yourself in godaddy, but im guessing its completly legal as long as your customers know and understand what is going on.
Also, if you want to become a reseller, the two major resellers are opensrs, and enom. Search the forums for these and youll find more than enough information.

Yeah we use e-nom also, its really quite good now they sorted out the javascript on the forms!!! lol

That sed you don't NEED a reseller package, ethically you should just list the client as the registrant, and where possible as the admin contact, (our clients generally request we stay as the admin contact, trusting off them....)

tech contact is your place, well it is if you maintain the DNS Zone data.

Providing Go-daddy lets you do this then there's no reason to stop, unless you need to automate large volumes of registrations.