Change tty terminal font size

sudo vim /boot/grub/grub.conf

add 'vga=796' at the end of kenel line
for instance:
kernel /boot/vmlinuz-2.6.22.5-76.fc7 ro root=LABEL=/1 rhgb quiet vga=796

what number should you use instead of 796? Check this page out:
http://en.wikipedia.org/wiki/VESA_BIOS_Extensions
or google VESA BIOS :-)

OK, some people, like me, don't use vesa driver. So what number should we use? check the following link out:
http://www.linuxquestions.org/questions/linux-hardware-18/terminal-window-resolution-better-than-80x24-63927/

Linux video mode numbers

The Linux kernel allows user configuration of VESA modes at boot time using the 'vga' kernel parameter. This parameter does not directly accept VESA video mode numbers; instead, a Linux video mode number must be calculated using the VESA number.

							1024×640	1024×768	1152×720	1280×1024	1440×900	1600×1200
16 color palette								772		774
256 color palette							874	773	869	775	864	796
15-bit (5:5:5)							875	790	870	793	865	797
16-bit (5:6:5)							876	791	871	794	866	798
24-bit (8:8:8)							877	792	872	795	867	799
32-bit (8:8:8)1							878	824	873	829	868	834

1: 32-bit is really (8:8:8:8), but the final 8-bit number is an "empty" alpha channel. It is otherwise equal to 24-bit color.