Best Mac OS X Softwares to send and receive messages

Free

ICQ is an open source instant messaging software.

Freemium

KakaoTalk (Korean: 카카오톡), or sometimes KaTalk, is a free mobile instant messaging application for smartphones with free text and free call features.

Free

iMessage is an instant messaging service.

Open Source

Rambox is a free and Open Source messaging and emailing app that combines common web applications into one.

Find apps to do interesting things:

Search for torrents online

Play MKV video files smoothly in high definition.

Organize your video collection.

Share files remotely with other people

share images, videos or audios with your friends and family.

Develop games for android devices.