Achievements

These are little badges of merit that can be earned while playing the game. As an incentive to earn them, you are given one free skill point per completion. There are 120 achievements altogether for you to unlock. Several new achievements were added to the game on October 16, 2009; at the same time, the ability to share a first-time achievement with your Mafia for a bonus was also added to the game. The bonus a player receives for clicking through a shared achievement is random, but includes a cash payout and one of several consumable items or an experience point bonus. Note: Some of the achievement sections are invisible to users that did not get any one of the achievments in that section. A former racket player (who was unable to buy or sell New York properties) will not see the Legacy Achievement section. The same applies to the Special Event Achievement section.
 * With the new properties upgrade, the Cashing Out achievement is now impossible due to selling being removed.
 * People who live outside the united states are unable to collect Three achievements: Mobile and Dangerous, Mobile Hit and Working Remotely
 * Pick of the Litter, Over Achiever and Green as Grass are achievements for a yet to be release feature. Some players managed to get this achievement on April 8, 2010 through a glitch in Mafia Wars.
 * Pick of the Litter, Over Achiever and Green as Grass are achievements have been temporary removed since 14 Apr 2010.
 * With the Fight Loot event introduction on June 16, 2010, four new fighting achievements were added.
 * 10 Las Vegas achievement added on July 21, 2010 (1 of them is still coming soon)

New York Achievements (17/17)
For an excellent article in how to legitimately get the What's After a Trillion achievement in just under a year, see this Mafia Wars Loot Lady's blog entry