One of the best pieces of time-saving filmmaking software available on the market is PluralEyes from Red Giant. PluralEyes takes out hours of time lost during the editing process spent synchronising audio and video.
Why Use PluralEyes?
Although specialty film cameras and even DSLRs have the capacity to record 
audio directly, the only way to credibly record audio is with a separate sound recorder. On professional sets, the recording device of choice is usually something from Sound Devices or a similar high-end manufacturer. At Elfenshot, we use a smaller handheld unit (Zoom H4N) which gives a reasonable result when paired with our Rode NTG-3 condenser microphone. Either way, the audio needs to be synced with the video during editing.
What Does PluralEyes Do?
PluralEyes is a program that automatically synchronises the separate audio and video files, negating the need to match up clapper boards and even timecodes. For $199 (US), PluralEyes paid for itself during a single short film. The interface is quite user-friendly, with a simple drag and drop process, which yields a fresh file with both files synchronised and ready to export directly to the NLE.