Want the fastest way to put your MAC into a deep, sleepy-bear hibernation-like sleep (no whirling fan, no dialogues, no sound — just fast, glorious sleep). Just press Command-Option and then hold the Eject button for about 2 seconds and Zzzzzzzzzzzzzz. It doesn’t get much faster than that!

Most email servers have a limit to how large an attachment they’ll accept. Most limit an attachment size to 5MB (some even less) and if you email somebody a 6MB file, it’s probably going to get “bounced back” to you as undeliverable.

Want to get around that? On your MAC, use iChat instead. Once you have an iChat session started with someone, you can go under the Buddies menu and choose Send File. Navigate your way to the file you want to send, click OK, and the file will be sent to the person you’re chatting with (and a link to download your file will appear in their iChat window). No matter how big the file size is, it’ll get there!

In Mac OS X, if you want more info on your files than the standard icon view provides (after all, it just gives you the file’s name in icon view)? Then turn on Show Item Info. This adds an extra line of information below many files and folders that can be very useful. For example, now not only do you get a folder’s name, but just below the name (in unobtrusive light-blue, 9-point type), you’ll see how many items are in that folder.

If the file is an image, the Item Info shows you how big it is. MP3 files show how long the song is. To turn on Item Info for your current Finder window, press Command-J to bring up its View Options. Then turn on the checkbox for Show Item Info. If you want to show the item info for every window (globally), then choose the All Windows button at the top of the dialogue window.

With Mac OS X, you can open many files in programs other than the ones in which they were created. For example, if you’d prefer to view an Adobe Acrobat PDF in the faster-loading Preview application, simply select the PDF file, choose Open With from the File menu in Finder, and choose the Preview application in the pull-down menu.

But what if you always want to open PDFs in Preview instead of choosing this application each time? Mac OS X offers an easy way to reassign all documents of the same type to open in the application you specify.

Let’s say you’ve saved several Adobe Photoshop files as JPEGs. In the future, you would like to open these files using Preview, rather than waiting for Photoshop to load. To reassign the default application simply select any one of these files, then go to the File menu in Finder and choose Get Info (or just select the file and type Command-I). Click the Open With disclosure triangle, if needed, to reveal a pull-down list of all the applications on your Mac that you can use to open this type of file.

Choose Preview from the list of applications, then click the Change All button beneath the application pull-down. (This button is grayed out until you select a different program than the one already assigned to open the file.) A pop-up will ask you to confirm that you want to apply this change to all documents of this type. Click Continue. Now whenever you double-click on one of these JPEGs, it will automatically open in Preview on your Mac instead.