We usually use ferrite beads as a power supply filter. You’ll find them on the USB supply in circuits with an FT232 USB->serial converter chip, like the Bus Pirate, and on the ethernet interface of the web platform.
For general purpose digital prototyping we just get something with a sufficiently high current rating and under 330ohms of impedance. When we moved to all 0603 parts, we picked up a few hundred of this 1.5A ferrite bead.
Some circuit might require a more carefully chosen bead, but most of our projects with run fine without the bead at all. If a specific bead is needed, the datasheet will usually list it.