Apple has the habit of giving several of its fine products the same name. The result is that each product ends up with several nicknames.
Power Macintosh towers have generally gone by their development code names: Gossamer, Yosemite, Yikes!, Sawtooth, Quicksilver, etc.
The Titanium PowerBook G4 has the almost universally understood nickname, "TiBook". It's cute, it gets the point across, and it produces a nice parallel with the iBook. Before its release, the TiBook was known by its mysterious code name, "Mercury".
There are no less than four products that go by the name, PowerBook G3. These are known by their development code names, as well: Kanga, Wall Street, Lombard, Pismo.
The newer iBook enclosure has been named the iceBook by users, for its frosty clear/white design. Official Apple documents, however, call it the iBook(dual USB), as if the addition of an extra USB port is the primary characteristic that sets these models apart from the original "space clam" iBook.
The old, circular, wind-up AC adapter that came with iBooks and PowerBooks for a while is often called the "yo-yo", for obvious reasons. The new, square white adapter is sometimes known as the "chiclet". The much-maligned circular mouse that came with the original Bondi Blue iMac, and later spread across the whole desktop line, is known as the "puck".