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 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!