Have you considered old school game programming ie vga based game? Or homebrew development for the GBA?
Another hobby thing you could look into is SIMD coding using intrinsics.
That sounds very interesting. How do go about doing that?
Are you trying to learn asm or just take a rest from your project? If this is just for short distraction then try something completely else ( I did that and keep coming back to it, also just for fun) - write something for any of old 8 bit consoles or computers. My favourite is Atari 2600 VCS and 6502 assembler language (look for Stella emulator, it's not only emulator, it's very sophisticated and full featured debugger! If only developers could have such tool in 80s ;)). VCS is very simple in terms of architecture, but because of constraints incredibly challenging (today if feels like solving a puzzle rather than making a game;)). This will not teach you any modern assembler, but will show you basics of ANY asm. For many years rules didn't change, while knowing 6502 you will be able if not write, then at least read modern asm code. It may appear very handy during debugging mysterious issues.
At first it was just a distraction but honestly after I made few small programs in assembly I really started loving the language. I will check out Stella.
Thanks ^_^