Another one of the neat little additions that come with Acrobat 6.0 is the option for selecting text using the Hand Tool. The basic idea behind it, it seems, is that if you're reading a PDF document, it's highly likely you will want to copy some of the text. Of course, up until Acrobat 6.0, this meant switching tools between the Hand and Select Text tools -- at times a real pain.
Press Ctrl+K and select General Preferences
Tick the 'Enable text selection for the Hand tool' checkbox
Hover over text with the Hand Tool to see the change
It's probably not for everyone though and can take a little getting used to -- if you're about to grab the page with the hand and it suddenly turns to a cursor, you'll have to wait a moment till it switches back, or you'll need to move your cursor to an area of the page that doesn't contain text. It's something I've gotten used to pretty quickly. Overall it's really worth a try if you regularly read, review and edit PDF documents.
Text Selection Margin Size & Column Selection Margin Size
The options in Preferences give you further control by letting you specify the distance in pixels that the Hand Tool needs to be to text or to a column of text before it switches to the Select Text Tool.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.