A webdeveloper was asked to do project management as well?! Hm, this is odd since doing project management puts you our of your primary domain - coding. Because of that it's almost impossible to say "what else you can add" to quoting. Basically with this approach you can add anything - make them morning coffee, massage them, etc.
Now, getting back to things a webdeveloper can offer, I'd say they are:
- web design
- optimization for mobile devices and tablets
- selling web domain
- basic web administration like the one you do for yourself on your own hosting server (like cPanel, etc.)
You may also add SEO, but that also out of web developer area.
Now, I may be too rigid since I don't know your capabilities. If you are capable of doing SEO and project management, then do that as well. But somehow, I think this may be too much for one person. Imagine 10 projects with all these tasks for one person only.
PS. Many times I also tried being a coder and project manager and QA to cut costs, but in the end neither of these task I was able to complete in a quality manner.