There are a number of OCR packages available that you can download, or get with the purchase of your scanner, but just about all of those seem to be dated the day you get them.
This service offered by Sci Weavers called i2OCR allows you to upload your scanned image in TIF, JPEG, PNG, BMP, GIF, PBM, PGM or PPM format, click on the "Convert" button and your text will be displayed for you on the left with a copy of your image on the right.
Why I liked this simple OCR tool is that it does the conversion without using your email address (which normally gets used for spamming you with all sorts of nonsense), it supports a good number of image formats and it also does columns. You also do not need to register before converting an image to text.
It does not give you the format of your document, like fonts, tabs and formatting - but for the quick text extract from an image file it seems to work rather well.
They don't charge for the service and there are a number of other conversions that are also available from the site. So if you are stuck with an image you want to extract the text from, give this site a try.