An XBOX with 128MB of RAM would run Fluxbox or whatever light env with ease, and with Dillo and a PSP user agent you could even post into HN. Gemini and Gopher would do it fine, even with clients written in TCL/Tk. It would be a fine backup PC for either thinkering or rescueing.
With ZRAM you could almost mimic a 192MB of RAM based device, good for maybe a browser like Seamonkey/IceApe if it could be built without SSE2.