Visor (a recent Pick of the Week here on macosxhints) is a must-have enhancement for OS X's Terminal.app. It has has just one annoying bug: It will get bigger by one row each time you relaunch Terminal. To fix this problem, the developer suggests that you manually edit Terminal's plist file in ~/Library/Preferences. Here's a trick that will do this for you.
prompt$ mv visor ~/.visorresetvisor() {
defaults write com.apple.Terminal VisorTerminal -dict-add Rows 20
~/.visor &
killall Terminal
}
Note: Replace the number 20 with whatever size you prefer Visor to have.Mac OS X Hints
http://hints.macworld.com/article.php?story=20070214223039729