I purchased an old Wyse Windows Terminal off Ebay for AU$ 100 (40£),
and connected it to the plasma in my living room. It's just visible, the small
black box, right of TV. Add a wireless keyboard and mouse and voila...

...the Internet (and our forum) from the couch.
The device has an old version of Internet Explorer so cannot display anything fancy like Flash.
Silent and low heat, you just leave it on. Just change TV source selector to get back to TV.