nq
These small utilities allow creating very lightweight job queue systems which require no setup, maintenance, supervision, or any long-running processes.
nq should run on any POSIX.1-2008 compliant system which also provides a working flock(2). Tested on Linux 2.6.37, Linux 4.1, OpenBSD 5.7, FreeBSD 10.1, and Mac OS X 10.3.
The intended purpose is ad-hoc queuing of command lines (e.g. for building several targets of a Makefile, downloading multiple files one at a time, running benchmarks in several configurations, or simply as a glorified nohup), but as any good Unix tool, it can be abused for whatever you like.