Fancy completion all over Emacs, not just for buffers and files. https://github.com/DarwinAwardWinner/ido-completing-read-plus

Ryan C. Thompson b626e03e87 Remove old magit override on init 10 years ago
ChangeLog a6f28fabb0 Document changes in ChangeLog 10 years ago
README.md c430dd331d Improve some documentation 10 years ago
ido-completing-read+.el 7239d809fc Many bugfixes 10 years ago
ido-ubiquitous.el b626e03e87 Remove old magit override on init 10 years ago

README.md

ido-ubiquitous

Gimme some ido... everywhere! This pacakge replaces stock emacs completion with ido completion wherever it is possible to do so without breaking things.

Get it from http://marmalade-repo.org/packages/ido-ubiquitous

Note that ido-ubiquitous is not enabled for org mode or magit mode, because those modes have their own built-in support for ido, which you should enable instead. Also, to enable ido for all file and buffer completion, customize ido-everywhere.