Contract Management

I own an outdoor advertising business and have been using Zoho Invoice for about 6 months. I must say that I love the functionality, ease of use and benefits it gives me. One major option that I could use is a module to management contracts. Some things I would like to have are: keep up with start and end dates, remind me when a contract is about to expire, be able to attach my docs to it, be able to add notes for potential new clients, etc. Does Zoho offer anything like this now? Can I add a contract management module to Zoho Invoice? What are other options to handle my needs if these options are not currently available? Any help or suggestions are greatly appreciated!!