curl and libcurl is a tool for transferring files using URL syntax. It supports HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP, POP3, IMAP, SMTP, RTSP, RTMP, and FILE, as well as HTTP-post, HTTP-put, cookies, FTP upload, resumed transfers, passwords, port numbers, SSL certificates, Kerberos, and proxies. It is powered by libcurl, the client-side URL transfer library. There are bindings to libcurl for about 40 languages and environments.
Dosage is designed to keep a local copy of specific Web comics and other picture-based content such as Picture of the Day sites. With the dosage command line, script you can get the latest strip of a Web comic, catch up to the last strip downloaded, or download a strip for a particular date/index (if the comic's site layout makes this possible).
Twisted is an event-based framework for Internet applications. It includes a Web server, an SMTP/POP3 server, a telnet server, an SSH server, an IRC server, a DNS server, a generic client/server pair for remote object access (Perspective Broker), and APIs for creating new protocols. It supports integration with GTK+, GTK+ 2, Qt, Tkinter, wxPython, Mac OS X (PyObjC) and Win32 event loops. It also supports TCP, SSL and TLS, UDP, Unix sockets, multicast, and serial ports. Supported protocols include HTTP, FTP, SMTP, POP3, IMAP, TOC, OSCAR (AIM and ICQ), SSH, DNS, IRC, NNTP, Jabber, SOCKSv4, Telnet, SIP (for VoIP), and XML-RPC and SOAP using external packages. Most protocols are supported as both servers and clients.
pyratemp is probably (one of) the smallest complete template-engines for Python (with about 500 LOC). It has a very small set of special syntax in the templates. This reduces complexity and the probability of bugs and lead to an easy-to-use and intuitive user-interface. It uses embedded Python-expressions (in a "sandbox"), is well documented, has full Unicode-support, and produces very good error-messages, which is very useful when creating new templates.