The Zotero community maintains active forums where users' problems are addressed. Browsing and searching the help forums can often help resolve even complicated problems. Getting Help with Zotero post to Zotero Forums.
Using Mendeley's groups functionality helps to manage and expand your research. Mendeley's Private groups offer a number of enhanced features to aid usability and collaboration.
EasyBib's blog is focused on helping EasyBib users. EasyBib put together a resource for folks to use for finding good EasyBib help.