I used a SparcStation 2 as an X terminal for several years in the late 1990s, having picked it up free as a student. Eventually PC monitors and my budget improved to the point that I retired it, but it was massively better than the cheap 14" CRT I had on my PC at the time.

I did have to contribute floating point emulation support to the Linux sparc32 kernel code, as otherwise the X server would occasionally crash when it hit a denormal number in the font rendering...