Sloth is an OS X application that displays a list of all open files in use by all the applications your user account is running on the system -- this list includes IP and Unix sockets, character devices, pipes and directories, and is generated via the powerful
lsof command line tool. This list is presented along with the names of applications using the file and their process IDs. Sloth makes it easy to find out which applications are using which files. Includes support for regex list filtering, process killing, sorting and more.
Sloth is written in Objective C for Apple's native Cocoa APIs. Sloth is free, open source software and is distributed under the three-clause BSD license.
UPDATE 24/02/2016: Sloth now has a new home on GitHub.
The latest version is Sloth 1.6. It requires OS X 10.8 or later and a 64-bit Intel Mac.Download: Application | Source Code | Old versions