squid_redirect uses a list of patterns to zap annoying ad banners from Web pages, inserting a placeholder image. It lives in a Web proxy and so requires no special browser facilities. It's readily customizable, small, fast, and easy to install. (In Debian/Ubuntu, this program is named "adzapper".)
Reapoff (Regular Expression, Arbitrary Protocol, Opensource Filtering Firewall) is a regular expression enabled TCP/IP proxy. It operates on data using a pair of simple rule- based configuration files defining the tests and actions to perform on data. It can also sign SSL connections transparently (with MITM), applying a security policy to encrypted SSL sessions that would otherwise be allowed unchecked. The proxy forms the core part of an overall firewall solution designed to run from a RAM disk using Trinux.
fk_html is a standard filter for incoming mail. It runs on your local machine as a fake POP3 server that redirects your mail client connections to your real POP3 server. Doing that it can scan, filter, and convert your incoming emails and is totally independent from your mail client type or version It provides multiple account settings, conversion from HTML mail to plaintext mail, removal of scripts from HTML mail and attachments, address filtering based on blocklist and allowlist, the ability to apply different policies to different accounts, and SSL support (also for non-secure clients, in which case only the loopback connection is not encrypted).
ShoutCastProxy is a system for saving bandwidth when multiple users in different rooms are listening to the same ShoutCast audio stream. ShoutCastProxy runs on a central server, and connects to whatever ShoutCast server that a client requests. If multiple clients request the same stream, the stream will be downloaded from the original source only once, but will still be sent to all the clients. Multiple proxies can be chained together.