Homebrew has the capability to add (and remove) multiple taps to your local installation with the `brew tap` and `brew untap` commands. Type `man brew` in your Terminal. The main repository [https://github.com/Homebrew/homebrew-core](https://github.com/Homebrew/homebrew-core), often called `homebrew/core`, is always built-in.
* [homebrew/apache](https://github.com/Homebrew/homebrew-apache): A tap for Apache modules, extending macOS's built-in Apache. These brews may require unconventional additional setup, as explained in the caveats.
You can be added as a maintainer for one of the Homebrew organization taps and aid the project! If you are interested write to our list: homebrew-discuss@googlegroups.com. We want your help!
* [InstantClientTap/instantclient](https://github.com/InstantClientTap/homebrew-instantclient): A tap for Oracle Instant Client. The packages need to be downloaded manually.
* [besport/ocaml](https://github.com/besport/homebrew-ocaml): A tap for Ocaml libraries, though with caveats, it requires you install its customized ocaml formula. Perhaps a template for more work.
* [osx-cross/avr](https://github.com/osx-cross/homebrew-avr): GNU AVR toolchain (Libc, compilers and other tools for Atmel MCUs, useful for Arduino hackers and AVR programmers).