It certainly is a nice idea, but there are a lot of caveats.
#1 - Trust. People will avoid open-source options if they don't want their source code to be shared. They would need to trust you not to share or steal their code.
#2 - Lots of bandwidth. My own personal projects take up several gigabytes, and there's a lot of transferring going on for art assets and the like.
#3 - Reliable network. If it goes down just once, people won't use it. I would be upset if I couldn't get at my source code.
And more...
Thanks for your reply.

If people choose their project to be closed source, no code will be transferred between the site (which is me..) and the project-owner. If, however it is open-source there will be an option to download/upload it. My application is for presenting and following development only, so I might just go with a link to the sourgeforge page where the project is located for developers (assuming that everyone uses sourceforge).
I have my website hosted in Denmark by One.com which is so nice to offer unlimited bandwidth, aswell as a guarentee for 100% uptime, to avoid problems for commercial sites. The only thing I'm concerned about is space. I do not have a lot of space, so if I reach a high amount of users/projects, with a high amount of pictures I will need to extend storage on my server (which I think would not be a problem with that amount of users, and google-ads).
It will be free, but I will have to show one ad banner per page, and that only covers storage. If my application did not have the option to upload pictures of your project, there would not be need for banners
Edit:I might have expressed myself oddly. There will always be options to upload your project if you wish to share it. If that is a closed source project, which for the example could be a game, you can upload your client, obfuscated, in a .jar, with only class files.
I mean that I'm most likely not going to support browsing code and developing, but downloading and following development.