I want to know, how important is it to program in your spare time? Is it necessary to work your 9-5 as a programmer and then get home and work on your hobby to become a better programmer? 

This said, I know you only get better at programming by, well, programming.

Do prospective employers take hobby programming into account in an interview or do they ask this just out of curiosity?

I feel guilty for not having a hobby project, but everything I can think of doing has already been done. So I am kind of in two minds about this, start something that has already been done or leave it until I come up with something original?


  I feel guilty for not having a hobby project


Feeling guilty is a crazy reason to embark on a programming project. Probably a good way to start hating programming, too. Work on something because you want to, not because you think you're supposed to.


  but everything I can think of doing has already been done.


Bah! Who cares if it's already been done? Do it again! Do it better! Or, accept that you may not be able to do it better and do it anyway. Where would Microsoft be if they said "well, someone has already created a database/spreadsheet/word processor/operating system/IDE/project manager/money manager/C-based single-inheritance dynamic object-oriented language/web browser/web server/music player/mobile platform/search engine, so we'll look for something else to do..."?

Seriously, if you write a web server, it's probably not going to out-perform Apache, but you'll definitely learn valuable lessons in the process. You're unlikely to outsell Angry Birds, but writing a simple little video game will teach you a lot too.
