Hashcat is cracking software designed with speed in mind. It utilizes OpenCL or CUDA to use CPU's and GPU's as compute devices. It supports Linux (native platform), Windows, and OSX, with emerging support for FPGA's. Hash support is done via modules written in OpenCL C or CUDA C, and supports over 300 hash types in it's base distribution. It offers builtin workload distribution, and session state saving so a run can be stopped, and restarted at a later time. Hashcat maintains an active (but brutal) community on the Freenode IRC Network, channel #hashcat. There is also a Wiki and active forum

John The Ripper

John the Ripper is a fast password cracker, currently available for many flavors of Unix, macOS, Windows, DOS, BeOS, and OpenVMS (the latter requires a contributed patch). Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix flavors, supported out of the box are Kerberos/AFS and Windows LM hashes, as well as DES-based tripcodes, plus hundreds of additional hashes and ciphers in "-jumbo" versions.

JTR discussion happens on both mailing lists and via the Freenode IRC Network, #openwall.

Elcomsoft Distributed Password Cracker

We dont know much about Elcomsoft Distributed Password Recovery, but if you have money to spend, you can buy this. We hear its quite popular within law enforcement. From the website: "Break complex passwords, recover strong encryption keys and unlock documents in a production environment. Elcomsoft Distributed Password Recovery is a high-end solution for forensic and government agencies, data recovery and password recovery services and corporate users with multiple networked workstations connected over a LAN or the Internet. Featuring unique acceleration technologies and providing linear scalability with no overhead, Elcomsoft Distributed Password Recovery offers the fastest password recovery by a huge margin, and is the most technologically advanced password recovery product currently available."