If you've ever felt frustration with traditional methods of composition and sound design then HighC from Thomas Baudel could be the answer to your prayers. This cool bit of software allows you to draw sounds onto a time-frequency graph that looks like a musical score using purely graphical tools such as moving, resizing and copy and pasting.

Despite the intuitive interface HighC boasts some sophisticated sound design tools such as additive, FM and granular synthesis - check out the free version (which is limited to using a 22kHz sample rate) here.