A good way to keep your current speed and not lose momentum is to jump and switch weapons when you are in mid-air. This trick comes in handy when you are being chased by someone in a Multiplayer game and you are low or have no ammunition for the weapon you are using.
Unlock Exclusive ContentAdded 3 Jul 2009, ID #4678
At the 'Main' menu select 'Excusive Content' and enter the code 735S653J. Entering this code will give you extra money for equipment in Single-Player. Extra money for characters in Multiplayer and weapons become silver in Multiplayer.