Several others here have suggested my favorite font already, the standard 6x13 "Fixed" bitmap font.

Pretty much every Linux machine has a version of this, but most modern Debians (and probably others) that ship with fontconfig have bitmapped fonts turned off by default for programs that use fontconfig for their font info (i.e., not xterm, but gnome-terminal, usually gvim, et cetera).

If you want to use Fixed and other bitmapped fonts and they're just not there, take a look in /etc/fonts/conf.d for a file named (something like) 70-no-bitmaps.conf, a symblink to the same filename in /etc/fonts/conf.avail. If you remove the symblink from /etc/fonts/conf.d and instead

    ln -s /etc/fonts/conf.avail/70-yes-bitmaps.conf \
          /etc/fonts/conf.d

fontconfig will cache bitmapped fonts for you. Then you'll just have to get it to update your cache with

    fc-cache -f -r -v

and you should be able to use bitmapped fonts like Fixed.

You can look for other bitmapped fonts on your system with

    fc-list ":scalable=false" family pixelsize

which prints out the family name and the sizes for which the bitmaps are available.

    set guifont=Fixed\ Medium\ Semi-Condensed\ 10

makes gvim look precisely like a terminal for me.