We've recently been beta-testing a new feature, which shows you the type of computer your clients access content with:

Why do you need this?
If a client views a questionnaire or proposal but doesn't respond right away, you can now tell if this was a just quick check on their phone, and reduce the agony of waiting to hear back from them.
In web development projects, this also lets you avoid surprises - do you need to support an unusual devices in a web design project?
Seeing if your clients prefer Macs or PCs, lets you know if they are secretly using an outdated version of Internet Explorer, or if there is an opportunity to upsell a mobile app.
As this feature develops, we intend to add functionality to let you see a client's preferred phone/browser, and track the location from where they look at questionnaires and proposals.