If you do any sort of experimentation with electronics, you at least need a voltmeter to see what’s going on. Beyond that, you would want an oscilloscope to graph changes in waveforms, along with a power supply, generator, and a number of other gadgets that you’ll eventually acquire when you have the need and money for them.
For all of that functionality in one package, the Omniboard — now on Kickstarter — gives you all of that and more for around $35. It can be used as a 3-channel oscilloscope at 10MSPS, a 5MSPS waveform generator, and a voltmeter that can read four channels at a time.
But that’s not all. The Omniboard is an AVR ISP programmer or an Arm SWD debugger, as well as an I2C/SPI host adapter. It can also act as a standalone device using an Arduino-style TFT touch shield, or can interface with a computer for even more features via its five GPIO ports and programming capabilities.