Project Huddle is a self hosted WordPress plugin that allows you to upload wireframes, designs or embed entire live websites so that your clients can provide feedback on them. All they have to do is click and type to provide valuable feedback, that is 1000 times better than dot points in emails or crappy screenshots.
Unbelievable price for what it does. Loads of docs available on their site so your team can work out how to use it with almost no input from you.
We've used it with several clients and even the non-tech-savvy have been able to work it out pretty quickly.