I have started using Basecamp recently to manage web design and development projects, inviting the clients in to see to-do items, milestones, and comments in a centrally shared place.

So far the clients have totally “got it”, although I suspect some inevitably will not in the future.

I have also been using the project file areas to keep documents reporting hours spent, billed, and so on – updated at the end of each day – which has kept things wonderfully transparent with clients.

The writeboards have been good for step-by-step tutorials for clients managing things like email account creation, or anything else they ask how to do.

The biggest lesson so far has been to have lots of milestones, and hook the todo lists up to them.

I agree with connecting To-Do lists with Milestones. We have 12 To-Do list templates that correspond with 12 Milestones.

Jon. Hope that this is on-topic.

Have you tried using ProofHQ to tie in design approvals with your clients. It lets you provide rich review and approval tools to your clients, and is integrated with your Basecamp projects. http://37signals.blogs.com/products/2008/07/proofhq-and-bas.html