One challenge that I find with old adapters is that they are not necessarily obviously connected to their host devices. It can take a bit of mixing and matching to find the adapter with the right connector. A benefit of USB charging (even if it is slow): I no longer need to worry about the voltage, pin-out, current, and connector type.
At least there is some standardization across product lines, e.g., Dell laptops and Motorola 2G phones like the RAZR (which adopted mini-USB). Second hand resale sites like Craigslist would be a great way to sell an old charger from a dead cell phone or computer (if it can't be used as a spare) and likewise, check on those sites before rushing off to Best Buy or Amazon.com ...
The market for power adapters is one of the tragic consequences of our disposable culture. Most of have enough discarded power adapters to populate a third world village - but each device requires a new incompatible one. Talk of standardization in telephone charger connectors (and the advent of USB charged devices) helps but we have a long way to go.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.