All but a handful of our clients are secret. As is the nature of the work we do for them. In the contracting business [*], this is the modus operandi. When people initially start working for us, they view the secrecy as a detriment - they feel it would so much easier to obtain new clients if we could talk about the clients that we already have, clients that are huge, well respected, leaders in their industries... This is short sighted however, in that while the name-dropping may initially make an impression on the potential client, that client also quickly realizes that soon enough their name would be used to gain some other client, something that would be great for Aspen Research, but of no value to the name-dropped client.
At the same time, the need for confidentiality about what we are working on is much better understood. As one of our former leaders said, we get to work with the crown jewels of a client's business. If the problem wasn't important, they wouldn't be hiring us.
Being owned by a larger corporation also presents additional challenges for us. We keep quite a distance from them both physically (i's 14 miles to their buildings) and structurally - their ID cards won't allow them access to our building and vice versa. We are not part of their R & D structure, but a separate entity that reports to the COO. We don't tell them what we are working on or who we are working for. The only restriction that they have on us is that we can't work for any of their competitors.
[*] Note that I said contracting business. We are NOT consultants - we work for a living.