CGNodes is the Render Time Calculator app for 3D artist.
The Estimate Render Time calculator estimate the time it will take to render your sequences and also include a predicted finish time of day.
The Allowable Frame Time calculator to work out what frame times are acceptable to get the sequence rendered in time! This is useful to make sure you render a full sequence overnight, or to hit a immediate deadline.
The Distributed Render Time gives you the same but with multiple machines for one or multiple frame, useful with V-Ray and other distributed capable engine.
The Shot Length is an easy way to transforme frames in readable time and inverse. You can adjust the FPS to match your need.
Finally, use the paperclip to save a custom machines number that feet your farm! Be careful with this one: it can also make you want to buy more hardware ;)