Allow clients to add their own service catalog items and route user requests internally or to other outside vendors. Offer a single source for end-users to get their problems addressed.
Allow clients to add their own knowledge base articles so they can answer more than just IT questions.
Allow clients to create their own training courses to help clients cover issues such first day on the job, benefits or workplace policies.
Allow clients to create their own IT policies that they want scanned in addition to your list of best practices.