A Simple Service For Extra Cash...
A lot of people, have a ton of stuff they've purchased just sitting around on their hard drive.
When you purchase developers rights to most plugins and themes, the terms specify being allowed to use/install it on clients sites. (developers licenses vary so check the terms)
This is an opportunity if you're just starting out, or need some extra cash, to offer this as a service on various 'gig' sites, or even here on the forum.
For instance, I needed a plugin that did something specific, and only needed it for this one site. I didn't feel like shelling out $47 and going through the whole sales process so I purchased the gig. (I made the seller prove to me he had a developers license).
Think about things you already have on your hard drive that you can turn into simple services, then take a couple minutes and throw it out there...
"May I have ten thousand marbles, please?"