Always, always, always put your code under source control. Being a one man shop is not a reason not to do it.
Take this comment serious. There is a statement that says: "There are 2 types of people. The ones that have lost data and the ones that still have to lose data." I fear I belong to both
I'm using 2 technologies for my arduino related code (read private time coding). 1 is github. If you want to share your code with the world; it is free (like in you pay nothing). If you want private code you have to pay. It has 1 drawback. you need to push your code yourself to the server.
For code I do not want to share; I use a cloud drive. It sounds similar as to the dropbox Targettio mentions. The biggest advantage is that code gets copied without any need for action on my part.
You can call me lazy... I call it convenient. The cloud drive I use is included in a server package so also free (Like in prepaid)
I don't know anything about cloud drive, but it sounds like a backup solution, not source code control. Ideally you want a source control archive that gets backed up automagically.
I have been dealing with this also, looking for something with near zero maint effort and free. As Maniac said, Git is the flavor of the year, but I don't agree that its easy to use. I have been doing some contracting work and they use Git Hub, and there is a learning curve. Also, Git hub is not really cheap for non-open source. In fact its a bit pricy.
The search continues...
That said, I don't really know what to try. Most of my development is done on a Windows platform so intergration with the file manager would sure be nice. Intergration with Eclipse is nice as well, but I'm not using Eclipse much lately.