But if you would like to experiment with computer architectures, you can get something like the Altera DE-2 [1] and play around with really crazy sauce kinds of things, n-way associative cache with CAM register banks and dynamic register renaming? No problemo! And you do it all without soldering or wire-wrapping or anything. I have some PDP-8's and I love them dearly, but it is soo much easier doing stuff on an Arduino than a PDP-8/e.
[1] http://www.altera.com/education/univ/materials/boards/de2/un...
So I went through an interesting series of transformations, first I was amazed about everything 'computer', I built my own Z80 machine, I ran through all of the languages that the mainframe the highschool had access too, I wrote games, "operating systems", computer languages, and various diversions just for fun. All the way through to about the mid-90's when I started working on the system that would become Java. The new stuff was fun, Sun's politics were soul crushing. I lost my sense of 'wonder' about doing cool things. It took me a while, wandering in the desert to realize that I was piling up all of these negative experiences against something I loved doing (systems design). I discovered it could be way fun to bring VMS up on an old VAX and show it off, to demonstrate active/active fail-over clustering on something as 'stupid' as a proprietary SCSI bus. The reason that was fun and 'regular' computers were not (to me at least) was that regular computers represented 'work' and 'the man' but these other computers were untainted. I committed myself to re-invigorating my 'wonder' and haven't looked back since.
It's a very different thing; I really love the fact I can do anything on something I can balance on my nose for an entire day, but fun wise I like soldering 74 series extending things. Being able to write an OS and understanding every single part of it, hardware and software.
Sure things are 'easier' now and that's a lot of fun for some things but I find it interesting and calming to leave the large amount of black box and extreme complexity in modern systems in my spare time.