irofferTNG is a new, more active branch of the iroffer development. Totally independant from iroffer, it is a more general-purpose bot. It uses loadable modules as plugins, with security and stability on mind. It has support for XDCC-style commands, very good performance serving multiple files through DCC, and a lot of cool features like DCC partyline, MySQL support, etc.
PircBot is a Java framework for writing IRC bots quickly and easily. Its features include an event-driven architecture to handle common IRC events, flood protection, DCC chat, file resuming, ident support, multiple servers, and more. Its comprehensive logfile format is suitable for use with pisg to generate channel statistics. Full documentation is included, and the Web site contains a 5-minute step-by-step guide to making your first IRC bot.