exceptions4c is a tiny, portable framework that brings the power of exceptions to your C applications. It provides a simple set of keywords (macros, actually) which map the semantics of exception handling you're probably already used to: try, catch, finally, throw. You can write try/catch/finally blocks just as if you were coding in Java. This way you will never have to deal again with boring error codes, or check return values every time you call a function.
SNeBU (Simple Network Backup Utility) is a backup system that supports incremental snapshot-style backups to disk-based storage. The project has been rewritten in C, and stores its backup catalog in an SQLite database. It features file level deduplication (including across multiple clients), compressed storage, incremental-forever snapshot style backups, simple setup, and utilizes standard TAR format. The client side consists of a simple shell script, which can be easily installed and adapted as needed. The server side is a single binary plus a config file, which can sit on a remote server and be accessed over SSH.
libnetfilter_cttimeout is an interface to Netfilter Connection Tracking timeouts. It provides a userspace library which provides a programming interface to the fine-grained connection tracking timeout infrastructure. With this library, you can create, update, and delete timeout policies which can be attached to traffic flows.
dwarves is a set of tools to inspect the DWARF debugging information inserted in ELF binaries by compilers such as GCC, and which are used by well-known debuggers such as GDB and more recent ones such as systemtap. With pahole, the struct packing and cacheline efficiency can be inspected.