If you're talking about an eSignature implementation that would work inside and outside your intranet then you are attempting something too ambitious. If you need eSignature type functionality I would suggest something like DocuSign.com. You definitely want to use an SaaS solution if you need external users in a future release. DocuSign now has a feature that allows document attachments btw. If you're just looking for a way to post documents and track viewing then I would suggest something like Acrobat Pro generated and eSigned PDFs that are posted on an Apache HTTP server. Turn extended access.log logging on and for intranet you could implement something like CA's SiteMinder for NTLM authentication and log the NTLM username/domain in access.log.

There's a free version of the expensive OmniFind product by IBM available with a little bit of Yahoo branding (which can be removed). You can't really integrate it easily with local search but I would assume that your users know whether they want local or shared documents. If you need security/permissions around people being allowed to access certain documents you're going to need to buy something. Otherwise try: http://omnifind.ibm.yahoo.net/

I'm not a DBC expert but when developing and designing projects I OFTEN use this paradigm when two or more developers are working on code. We separate the work that needs to be done and create "contracts" (in java we just use stubbed out classes that return dummy data) so that we can both work in tandem and integrate later. If the project is larger and involves web services there is the obvious WSDL contract that is always negotiated before-hand. If you're building your web-service and generating your wsdl then you've made a choice not to negotiate your contract and hopefully are not a very large producer because small changes in your framework could cause your clients to be forced to upgrade (this isn't a large application best-practice).