10. Add USB 3.0
When my EliteBook came out three years ago, USB 3.0 was a luxury, but now even budget machines use this faster standard. Happily, the system has an ExpressCard slot that can take a USB 3.0 adapter card. (Unfortunately, a regular PC Card slot isn't fast enough to keep up with USB 3.0.)
There are a variety of cards available from vendors like Sonnet and Sabrent; I opted for StarTech's $32 2-port ExpressCard adapter.
I loaded the software, inserted the card in the ExpressCard slot and let the hardware install itself. Once installed, the card's two USB 3.0 ports increased throughput with an external drive from 26.6Mbyte/s to 87.1Mbyte/s, more than a threefold improvement.