<p>I am new to sharepoint development but have about 10 years of expirence in C++, VB6 and C#. It is my experience that a great way to learn a new language or coding style is to spend some time "dissecting" one of the open source projects available at CodePlex or Google code. 
In order to avoid picking up some bad habits without knowing it, I would like to hear which projects you can recommend.</p>

<p>TIA</p>

Generally speaking, SharePoint "code" will come in the form of web parts and pages that are written for specific SharePoint installations. However, that doesn't mean that there aren't any SharePoint utilities and libraries out there.
In fact, I'm a big fan of
SmartPart
, which is hosted on Codeplex. This is a very useful SharePoint tool with a lot of downloads and some bugs that need to be fixed, so it's a great project to serve as your reference point
and
submit some code to!