sydbox is a ptrace-based sandbox implementation. It intercepts system calls, checks for allowed filesystem prefixes, and denies them when checks fail. It has basic support for disallowing network connections. It has basic support to sandbox execve calls. It is based in part on catbox and strace.
PinkTrace is a lightweight C library that eases the writing of tracing applications. It consists of Wrappers around different ptrace() requests, an API for decoding arguments (strings, socket addresses, …), and an experimental API for encoding arguments. PinkTrace aims to be a cross-platform library for writing tracing applications.