JollysFastVNC is a VNC (virtual network computing) client for the Mac. It is a safe and fast app that lets you connect to any VNC server, be it on a Mac, Windows, Linux, or any other device that supports the protocol. The application is not free, but it is regarded as one of the best and most popular VNC clients on the Mac.
I have used JollysFastVNC and there are two things that I really liked about it. First, it is really secure; it supports SSH tunneling, SSL, and SOCKS. Second, it uses Bonjour to find computers on your network, and it lists them so that you can quickly and effortlessly connect to them. Another interesting and innovative feature is "SmartZoom". Basically, it stretches and zooms the area of the server that your mouse is currently on. This is a great feature for large remote desktops. There is also support for Wake-on-LAN, which lets you wake up computers remotely, if they are configured to do that.
All in all, this is a great commercial VNC client. You can try it for free and purchase it through the Mac App Store.