Macintosh Portable - 1989
The Mac Portable (aka "Mac Luggable") was Apple's answer to the growing cry for a portable Mac in the late 1980s. Essentially an SE in a suitcase, the Portable had a great keyboard, backlit screen, a built-in trackball and vintage Apple styling. Unfortunately it was also heavy and expensive, and not a big seller in its day. The Portable attained a strong cult following over time, and today has become a valuable collector's item. Its lead acid batteries pack real heft and never fail to impress visitors to the Museum!

This Mac Portable utilizes the System Picker application to choose between three startup choices: System 6.0.8, 7.1 or 7.5.5.

PowerBook 170 - 1991
The PowerBook 100 Series replaced the Macintosh Portable with a truly portable system, and was the first incarnation of the PowerBook name and battleship grey color. The form-follows-function design was rugged and popular, lasting several generations. The 170 hit the market with a powerful 68030 CPU, built-in modem, 2.5" laptop SCSI hard drive and an active matrix screen, making it a favorite for business users, writers and students alike. This form factor lasted for several generations, topping off with the color model 180c. The VMM 170 runs System 7.1

Personally, I remember having my first case of PowerBook Envy at about this time... VMM TV: What's on your PowerBook?

PowerBook 540c - 1994
Radical in its day, the PowerBook 500 "Blackbird" series took the Quadra on the road in style. The 540c offered an active matrix color screen, 68040 CPU, a trackpad, dual battery bays, 16 bit stereo sound and built-in ethernet, along with a bold new case style that influenced PowerBook models all the way through to the PowerBook G3 "Pismo" years later. Like the 840AV on the desktop, the 540c represented the pinnacle of 68k PowerBook design.

The 540c runs Mac OS 8.1 has served a vital role on the VMM network, capable of mounting 3.5" floppy disks as well as accessing AppleShare volumes from Mac OS versions 7, 8, 9 and X for inter-generational filesharing.

PowerBook 2400c/3400c - 1997
The early PowerPC era wasn't kind to Apple, and PowerBooks were hit hardest. After a disastrous experience with the lackluster, sometimes flammable 5300 line, Apple released the x400 series of portables (1400, 2400, 3400). The 3400c was built for speed with a 240MHz PowerPC 603ev (low power) processor, which Apple claimed at the time was the fastest portable computer in the world . An expansion bay supported CD-ROM and floppy drives, and an active matrix screen made this a useable if somewhat beefy portable. The 1400c was a budget model with a nice keyboard, while the 2400c was a subnotebook that was scarce in the US but very popular in Japan - the MacBook Air of it's day.

PowerBook G3 "Wallstreet" - 1998
With the G3-based Wallstreet, the PowerPC PowerBook finally hit its stride. Sporting a striking jet-black Batman'esque case, 14" active matrix screen, 2 PC card slots and dual expansion bays with lots of options (CD-ROM, DVD-ROM, Floppy, Zip, SuperDisk and later CD-RW drives), the Wallstreet (Apple's internal project name) was built like a tank and a pleasure to use. SCSI, ADB and serial ports gave full compatibility with existing peripherals for desktop machines, and it was a big seller. Like many early G3 systems it was underpowered for Mac OS X but makes a very good Mac OS 9 system.

At the VMM a Wallstreet runs Mac OS 9.2.2 and serves the primary computer for Oakbog's vintage file transfer efforts: it can bridge the worlds of floppy disks, SCSI drives and Ethernet. This model was a tank and is still a pleasure to use.  
VMM Blog: Vintage Mac Museum Workhorse - Wallstreet

PowerBook G3 "Pismo" - 2000
Two generations after the Wallstreet, Apple introduced the Pismo. An ultra-refined and minimalist design, many Mac users (this writer included) consider this to be one of Apple's most attractive laptops. The Pismo (officially the PowerBook G3 "FireWire") dropped ADB & SCSI in favor of USB & FireWire, but retained the dual battery/expansion bays and curvy styling first introduced with the 540c. A good dual-bootable Mac OS 9/Mac OS X system, the Pismo was Apple's last black computer until the Intel-based MacBook (Steve hates black). It remained popular for years and still retains decent resale value.

The VMM Pismo runs Panther and provides wireless internet access in the bedroom and other important locations...
VMM Blog: Pismo - We Can Rebuild Him

PowerBook G4 "Titanium" - 2001
How do you make a product smaller and larger at the same time? If you're Apple, you make the case thinner and the screen wider. Add a processor upgrade and another stunning new design (often imitated, never duplicated) and you've got the PowerBook G4 Titanium. The "TiBook" needed a few iterations to get the bugs worked out and it didn't include any expansion bays, but was slim, lightweight and the PowerBook to have among Apple cognoscenti. Shortcomings included an easily scratched exterior, poor WiFi reception (a metal case will do that) and a weak hinge design, all of which were improved in the PowerBook G4 Aluminum series a few years later.
 

PowerBook G4 "Aluminum" - 2003
Citing changing usage trends Apple declared 2003 the "Year of the Laptop" and revamped the PowerBook line to include a variety of sizes. The G4 Aluminum came in 12", 15" and 17" sizes, was sturdier, more scratch resistant and had better wireless reception. The formerly removable keyboard was now permanent, resulting in a notable typing improvement, and like most Apple products had superb fit and finish. The 15" and 17" were reused in the Intel-based MacBook Pros; the popular 12" form factor, Apple's smallest-ever laptop, was discontinued. G4 Aluminum systems are the last portables to use the venerable PowerBook name. VMM TV: PowerBook G4 "Big & Small"