Most importantly, please make sure you include all the information requested. If you have questions, please ask email@example.com (list info here).
Please note that you are not bound to use these ideas, you can propose a new project. It is a good idea to find a mentor and discuss the idea before submit it.
GNU is a large and complex project, and thus is subdivided into packages, which are relatively independent projetcts. In Summer of Code, GNU acts as an umbrella organization for its packages. The ideas here are grouped by package. Many packages have more than one suggestion, or even their own ideas page.
Guix is a distribution of the GNU operating system developed by the GNU Project—which respects the freedom of computer users.
GNU poke is an interactive, extensible editor for binary data. Not limited to editing basic entities such as bits and bytes, it provides a full-fledged procedural, interactive programming language designed to describe data structures and to operate on them.