You can also use your end of year pay stub to do your taxes.
No, no, no, no, no!! I think you and I have this discussion every year but advising people to do their taxes based on their paystub is flat out wrong. Everyone's tax situation is different.
http://blogs.hrblock.com/2014/01/16/tax-myth-using-a-paystub-to-file-instead-of-a-w-2/
Your paystub shows your gross earnings. This may or may not be the same as the taxable earnings in the W-2. On mine, my YTD total on my paystub will not match my Box 1 Federal taxable wages and there will a completely different number in Box 3 & 5 FICA and Medicare taxable wages. This is because I have certain pre-tax items such as insurance premiums, HSA contributions, 401k contributions, etc.
You and I may be tax savvy enough to know what items to back out of gross wages to arrive at the proper taxable totals but not everyone is. Places like H&R Block, Liberty, Jackson Hewitt, etc will not file your tax return until you have the W-2. They may run a calculation based on the paystub but they will not press the button to actually file without all of the official documentation.