The ATTINY85 is a gem of a microcontroller. Its the “Nifty Fifty” of chips: cheap, small and versatile. This 8pin package is not the most powerful thing on the block but for good enough for most hobbyists and there are a million and one tiny projects that this is fully capable of running. And at $1-$2 a pop, its really hard to beat. Its almost disposable if you order a bunch for all your random little projects. It does take a bit more setup than an Arduino to get it running, but there are lots of easy to follow tutorials on the internets for people to follow. If you have an Arduino sitting around, its quite easy to use it to program the chip as well.
Most of my hobbies don’t get along with my bank account so its nice to find the little things that can be so interesting. So pick up a few and whether you make something useful or just plain silly, rest assured, it’ll be fun!
Inspiration here: ATTINY85 on Hack-a-Day