When a website is finished and approved ( and this is the correct way to do it ), it should be accompanied with a couple of services that can help both you ( as a website developer ) and the client at the same time. Here is a small list of what I think is important :
1. web hosting access
2. Google Analytics
3. Google Webmaster Tools
4. Bing Webmaster Tools
5. Back-End access
In short, web hosting access is like giving the key to the one that just rented your house, something you must do and that is only logical. Google Analytics is the tool that will help your client understand his audience and how it behaves within the website. Google Webmaster Tools and Bing Webmaster Tools are, for me, maybe the most important tools for the webmaster and the developer, both for SEO reasons but also for monitoring and information ( and tips also ) gathering. Back end access is also essential for your client so they can edit content at their discretion.
Those tools above and especially the "Access" part is important not only so to make your client feel ( and indeed do ) they are the masters of their website but also for later developers or SEO agents that will need such access and tools to carry out their tasks.
Being a professional in the world of web development and design, contains this little piece called "provide your client with the important services anyway".