Disclaimer -- As some of you may have noticed, I now write the Beating the System column for MacUser. I don't know what to disclaim, but since I'm identified as the editor of TidBITS at the end of those columns, it seems only right to mention it here. Writing for MacUser is different in that I have an approximately four month deadline for MacUser and a one hour deadline for TidBITS. That said, check it out and see what you think of my writing when I have a word limit and a professional editor.
Enabling Auto Spelling Correction in Snow Leopard
In Snow Leopard, the automatic spelling correction in applications is not usually activated by default. To turn it on, make sure the cursor's insertion point is somewhere where text can be entered, and either choose Edit > Spelling and Grammar > Correct Spelling Automatically or, if the Edit menu's submenu doesn't have what you need, Control-click where you're typing and choose Spelling and Grammar > Correct Spelling Automatically from the contextual menu that appears. The latter approach is particularly likely to be necessary in Safari and other WebKit-based applications, like Mailplane.