Both hardware and projects are more or less useless IMO. Almost everything we do is hardware, and concern a project of some kind. Tags should help you to find a particular question. What's the use if there are 1000 questions and looking up hardware questions would return 950 hits?
So I propose to delete them.
Let's throw in circuit-design as well. Er, by "in" I mean "out". You know what I mean. :-)