I would like to be able to create permanent projects with my arduino Nano but be able to remove the nano in order to use it in other projects. The arduino Nano has 30 pins so I would be looking for some kind of female 30 pin header. Most of the headers that I found like that are too narrow because they are for IC's. Any ideas?
The Nano boards that I have used all have pins on 0.1" (2.54mm) spacing. There are single-row female connectors that are designed to accept 0.025" square pins. One example is Samtec 32 position female header but there are many others.
Note that these female headers are available to accept either 0.018" round or 0.025" square pins. My great preference is for the 0.018" round pins but those are less common in hobby circles.
The really huge advantage of the smaller round pins is that you can safely insert them into solderless breadboards without damaging the contacts in the breadboard. But you would want to standardize on one style or the other.
I use the female headers from the original Nano manufacturer: http://gravitech.us/2015feheanas.html
You've already got a lot of really good answers here but I thought I would offer another product suggestion. I purchased some of the 12 pin versions of these https://www.pololu.com/product/1031 for some recent projects.