Post-Installation Notes for Mac OS X Leopard

Make the menu bar opaque

Check the checkbox at the bottom of Desktop & Screen-Saver in System Preferences.

Get back the 2D dock

defaults write com.apple.dock no-glass -boolean YES
killall Dock

Disable delayed TCP acks

They make the performance of Samba/CIFS file transfers really slow.

x="net.inet.tcp.delayed_ack=0" 
echo "$x" | sudo tee -a /etc/sysctl.conf
sudo chown root:wheel /etc/sysctl.conf
sudo chmod 0644 /etc/sysctl.conf 
sudo sysctl -w "$x"

Fix iTunes

Not really an OS X thing, but whatever…

defaults write com.apple.iTunes show-store-arrow-links -bool FALSE
defaults write com.apple.itunes show-genre-when-browsing -bool FALSE

Enable full keyboard access

System Preferences → Hardware → Keyboard & Mouse → Keyboard Shortcuts → Keyboard Navigation → Move between controls or text boxes and lists

This enabled you to tab between all buttons in windows. Detailed instructions courtesy of Mathias Bruce, thanks!

Change the Time Machine backup interval

sudo defaults write \
  /System/Library/LaunchDaemons/com.apple.backupd-auto \
  StartInterval \
  -int NUMBER_OF_SECONDS