Dummy data class https://github.com/fzaninotto/Faker
PHP Imap class https://github.com/tedivm/Fetch
TravisLight [https://github.com/willdurand/TravisLight]
Twitter status update [https://packagist.org/packages/dg/twitter-php]
Posmark/Sendgrid etc mailer api [https://github.com/henrikbjorn/Stampie]
Country List [https://github.com/umpirsky/country-list]
Kint - debugging helper for PHP developers [https://github.com/raveren/kint]
PHP Domain Parser - [https://github.com/jeremykendall/php-domain-parser]
Skype Emoticons [http://factoryjoe.com/projects/emoticons/]
Latin strings to translit [https://github.com/jbroadway/urlify]
Sitemap generator [https://github.com/ThePixelDeveloper/Sitemap-v2]
Geocoder [https://github.com/toin0u/Geotools]
Encryption lib by ircmaxell [http://stackoverflow.com/questions/5089841/php-2-way-encryption-i-need-to-store-passwords-that-can-be-retrieved]
PHP Reqsue (queue using Redis) [https://github.com/chrisboulton/php-resque]
OAuth [https://github.com/themattharris/tmhOAuth] Example: [https://github.com/themattharris/tmhOAuth-examples]
PSR-0 Payments - Omnipay [https://github.com/adrianmacneil/omnipay]
Twitter OAuth PSR-0 [https://github.com/ruudk/twitteroauth]