Here are some of the features of SoundBoard FX:
All your sounds in one place.

With SoundBoard FX, all of your sound effects are right in front of you. You can easily rearrange the order to fit your needs. Plus, all your audio files are embedded in the soundboard, so you don't have to keep track of the original files. 

Timing is everything.

When you need to know how long an act is, or when it's time to "take 5", the Clock/Stopwatch widget is there to help. With an elegant simplicity it tells you what you need to know in a small, unobtrusive window.

Control at the tip of your fingers.

Easily set custom shortcuts to play your various sound effects. For example, you can set "a" to play ambiance or ⌘+L for a laugh track. It's all up to you.

Brighter isn't always better.

When working in a dimly-lit environment, glare from a bright screen can be a serious nuisance, and can lead to headaches and eye fatigue. Switching the app to Theatre Mode changes the color scheme to a low-light, high-contrast appearance that's easy on the eyes.

Noteworthy sound cues.

Sometimes, more detail is better. Each sound effect has a note field that allows you to keep notes on timing, visual cues, sound description, and more.