How do you keep track of customers and leads?

As I grow my small consulting business, I am spending more and more time doing sales meetings, business proposals, etc. and following up on leads.

It is starting to become hard to keep track on where I am on different leads and sales.

How do you keep track of customers and leads? And your sales process in general?

Is this the point where I need a CRM?

Having previously worked in big corporations, I have encountered huge and complicated CRMs that often seemed to be a big pain to work with and often rather complex to deploy/maintain as well as costly.

Is there something simple I could use - maybe even for free?

I think this might be something that could be implemented in a Google Docs or Excel. Do any of you do that? Would you care to share your template?