From capacitor input filters, wall-warts and bench power supplies, all electronic projects have one thing in common and that is they all require something to power them! A bench power supply is one of the most vital tools to have on your workbench as it just makes life simpler and prototyping much quicker.

A bench power supply with variable voltage, current limiting and dual positive and negative fixed voltage regulators is even more handy to have for electronics projects operation based on amplifier (op-amp) integrated circuits, testing the dropout voltage of a regulator, determining LED forward voltage and limiting the amp current so your project won't blow up into smithereens!

You can do cool things with bench power supplies like hooking them up in series or parallel to increase the voltage and current respectively. Depending on the model you want, you can pick up a basic linear bench power supply without any fancy features (like computer control) very affordably.

With that said, you can never beat the build quality and affordability of buying an old-school bench power supply like the +Hewlett-Packard 6236B triple output power supply, which has a switchable range on the voltmeter for low-voltage use.

While vintage power supplies are analog, you can always digitize very inexpensively an analog power supply by mounting a volt/amp meter panel. Here is an example of how an inexpensive volt meter panel is hooked up to a 50 year-old analog power supply:
Vintage stuff may not be everybody's cup of tea but one cannot really deny the cool factor of the analog power supply shown in the video above, not to mention the excellent build quality and cost savings of buying vintage power supplies. Besides, there is nothing like giving old stuff a new lease of life by injecting a touch of modern!
With that said, if you are a hobbyist who primarily works with 3.3 volts, 5 volts and 12 volts there is another power supply alternative you can consider and that is building your own bench power supply or buying an ATX breakout board.
Most computer power supply units (PSU) use the ATX motherboard configuration specification, which produce +3.3 V (orange cable), +5 V (red cable) and +12 V (yellow cable) outputs. By the way, the ATX stands for Advanced Technology eXtended and was developed by +Intel in the late 1990's.
Using an ATX breakout board is definitely the easiest way to convert an old computer power supply into a bench power supply as you won't have to fiddle around trying to find which wire is which. With an ATX breakout board, you will be able to use any ATX power supply you want without having to clip off the ATX power supply connector and ruin the ATX power supply for any other uses.

ATX breakout boards are easy to use and you simply insert the power connector from the computer power supply into the breakout board and you have yourself a variable voltage bench power supply in seconds. There are several ATX breakout board solutions out there and two that I like are the ATX breakout board from +Dangerous Prototypes and the ATX breakout board currently being funded on Kickstarter.
The ATX Breakout board on Kickstarter looks quite neat and it is compatible with 20 pin and 24 pin ATX power supplies and has other cool features such as 5Amp USB charging port and 4 pin connector to take advantage of the 12V CPU power for extra current output.

The ATX breakout board from Dangerous Prototypes also outputs 12V, 5V, and 3.3V but has -12 Volt output too, as well as screw banana terminals and separate LED indicator lights on each voltage channel so you know when each voltage is working and when there is a shortage.

As a hobbyist myself who enjoys hobby electronics, I can see the versatility of a bench power supply. You can use a bench power supply for anything from battery charging and powering projects to independently test components and doing small electronic repair of domestic appliances.