Here is a great article about the true cost of Technical Debt by Aaron Erickson. The author gives a good example of the cost over time and relates it to Financial Debt in a way that should make sense to management and appropriately supports the metaphor.
I read another article of his that talks about killing the project in favor of small releases. That was great too and can be found on the same site.
When I read the example of commissions, I immediately thought of a commission service that could be called from anywhere on the intranet to calculate commissions for the company. I thought of reports and of SSRS reports and realized how far behind it would be to write reports with a technology that does not support services as data sources.
Wouldn't it be great to write some business rule in a first class code language and have all consumers call that centralized logic to do the processing? It would be contained in a service of course, not in a DLL or some other form of shared code; if it were, each place that uses that code would have to update in order to get the new rule. So your change would still involve some Technical Debt a la Architectural Debt (your architecture introduces more future work required to change some core business logic that can change). IDesign refers to this likelihood of change as volatility.
This volatility factor is a natural occurrence in software, whether recognized or not. Martin Fowler points out that this type of ignorance is wreckless, it is likened to going on a shopping spree and maxing out credit cards that you don't know you have to pay back. Then you will get the calls from the bill collectors. "The business needs to change xyz factor to yyz factor and now!" So now you don't sleep for a week and everyone is run ragged and angry because of this inexperience that cost just the right price.
In the case of Aaron's article, huge deals can run afoul and what was once an exiting merger can turn into a costly technical nightmare. I would like to hear of an example where this was the case. Office Depot and Office Max merged recently and stated the projected costs and benefits of the synergies of the merger. I wonder how that is going from a technical standpoint...
If I find anything, I'll surely have to blog on it.