Sysdig is open source, system-level exploration: capture system state and activity from a running Linux instance, then save, filter and analyze. Think of it as strace + tcpdump + lsof + awesome sauce. With a little Lua cherry on top.
A Middlebox Detection Tool
Observes filesystem changes using the same underlying API as Spotlight Provides a graphical representation of the file activity
mod_pagespeed improves web page latency by changing the resources on that web page to implement web performance best practices.
Skipfish is an active web application security reconnaissance tool. It prepares an interactive sitemap for the targeted site by carrying out a recursive crawl and dictionary-based probes. The resulting map is then annotated with the output from a number of active (but hopefully non-disruptive) security checks. The final report generated by the tool is meant to serve as a foundation for professional web application security assessments.
DKIMproxy is an SMTP-proxy that signs and/or verifies emails, using the Mail::DKIM module. It is designed for Postfix, but should work with any mail server. It comprises two separate proxies, an "outbound" proxy for signing outgoing email, and an "inbound" proxy for verifying signatures of incoming email. With Postfix, the proxies can operate as either Before-Queue or After-Queue content filters.
Maatkit is a collection of essential command-line utilities for MySQL
