I'm a physics student facing unemployment for the coming summer. I made it to couple of interviews but it seems that didn't get the positions because of lack of actual real world programming experience even thought the positions were aimed for a physicist. Well, I thought that now that I have lots of free time next summer, maybe contributing to some open source project would be a good way to gain some programming experience. Are there any open source projects especially suitable for a physics student? I know the basics of programming and the only way forward would be by getting involved in development of a larger application than I have come across during studies. I have no experience in developing GUI-based apps though so this is a limitation.