Over the two years I've worked at my library, I've seen an increasing number of patrons bringing in their own laptops. We've offered wireless access and many years, but now we're offering just a little bit more.
In addition to work tables in the library, we also have a number of study carrels for people to use. The tables we purchased were designed with both power plugs and ethernet jacks built into them, but the study carrels were not. Since the study carrels were near walls that had jacks, we thought that was good enough.
However, the arrangement of the carrels (which are two little cubicles arranged back to back) meant that one patron had easy access to the plug, while the other had to interrupt the first patron and loop wires over the walls to get access.
We thought we could do better than this, and set about checking our vendors and the internet for purpose-built after-market power boxes, that had both AC power and an ethernet jack - and that were low-profile enough to not encroach on the desk space. We found some, but most were $200+, which was too much. So instead, we built our own.
Using pieces and parts from the hardware store and Radio Shack, we made four boxes, one for each carrel, and each box had two power plugs and one internet jack. The pieces are all common and low-tech, so assembling them was no problem. And, not including ethernet cables (which we already had), they cost about $25 each.
So now, for a very low price, patrons can use their laptops with or without a wireless card, and with or without their battery power (as well as charge their cell phone or power some other device) and not have to drape cords over another patron.
That's one small step for the library, one giant leap for the patron who kept asking us why we didn't have outlets in the carrels.