If you are music lover and specifically look for online tools which can help you getting new ideas for music you definitely going to love this simple sine wave synthesizer- Tone Matrix.
This is ordinary 16 X 16 matrix sheet on which any block can be turned on or off. Turning it on starts music tone which sends out waves. When this wave hits another block which is on it creates a Wave Map.
The more the block you select together, stronger the wave is and better the rhythm. This does not mean you select all but keep variations which will make the music beat sound good. In fact this tool is so addictive that you can keep on trying new pattern and see how it goes. Try Tone Matrix