One example of this was the parallel universe of FireWire hubs. If you think of FireWire as "a big USB" then a hub wouldn't seem so strange, but FireWire was actually meant to replace SCSI. SCSI and FireWire are peer-to-peer: any device on the bus can talk to any other device, unlike USB where each bus has at most one host and the host does all the initiation of data transfer. (USB On-The-Go still has one host and one host only; it just allows certain devices like your mobile phone to swing both ways.) The point-to-point capabilities of USB 3 notwithstanding, a USB hub has one upstream port for the host and multiple downstream ports for the devices. A FireWire hub, however, is like getting a longer internal SCSI cable; more devices simply exist on the same bus. Connecting multiple FireWire hubs just makes a bigger bus because all the ports are the same.
However, this difference was mostly lost on consumer users because a FireWire hub, possibly intentionally, superficially resembled an oddball USB hub with weird connectors and a higher price. And both existed largely for the same reasons, first and foremost to give you more ports, and secondarily also to inject power into the system where multiple bus-powered connections could make voltage sag. (They could also improve stability by smoothing out impedance mismatches between controller chipsets, which solved an issue with my Sawtooth G4 freaking out when I connected two FireWire drives to it directly, even though they were both self-powered and the effective topology with a hub was still the same.) Nevertheless, FireWire hubs were absolutely distinct devices and at least in some respects catered to different markets. So what did this parallel universe look like?
Belkin was probably the most prolific manufacturer of consumer-level FireWire 400 hubs. These were targeted mostly at Mac users, though they would work just fine with PCs. Their first product was the F5U524, which was a four-port powered FW400 system (one port connected to the computer, so you got three extra ports). They sold far more of the F5U526 6-port hubs, though, and the most common form factor was this one:
Nearly as prolific was Kramer Tools, who still specialize in high-end A/V hardware. In addition to their rack-mount FireWire switchers (controllable by IR remotes or RS-232/485) and FireWire active repeaters, they made four-, six- and even eight-port powered FW400 hubs intended for prosumer and professional studios. These were definitely not Best Buy specials. Made of durable steel, you'd probably fracture someone's skull if you lobbed it at them. Their eight-port FW400 was the biggest FW400 hub I could find advertised.an eBay auction (not mine, not affiliated); hope they don't mind.
Potentially the most outrageous FireWire hub (thanks jonahjoselow) was the Hubzilla. It's like it sounds: Godzilla with four FW400 ports embedded in his spine. I would destroy cities too if I were subjected to this sort of torture. (Image from PCWorld.)any actually got sold.
As a degenerate case some FireWire devices offered daisy chaining with input and output ports, which could be considered a two-port hub of sorts (just one port being the internal device); the Lexar Professional Compact Flash card reader (shown here) and the Iomega Minimax are examples.
As FireWire devices became less common, some manufacturers perceived a market for dual hubs — i.e., USB 2.0 and FireWire hubs in the same physical unit. These were not complicated devices technologically because they weren't anything more than two devices on one board in one case, with a plug each for the USB and FireWire sides, and they don't convert USB to FireWire or vice versa. All of the combo hubs I've personally seen have four USB ports and three FW400 ports, like the IOGear GUH420:
Additionally, unlike the FW-only hubs which universally offered an external power option, some of these were powered and some of them weren't, and almost all of the ones that were powered only seem to power the USB side (the tipoff is the wallwarts only provide 5 volts, not 12). The same basic notion was used by devices from Hewlett-Packard (targetted at Windows PCs, with a micro-USB jack for the PC connection) and zombie-Compaq after HP bought them. SIIG sold an internal USB-FW hub for 3.5" drive bays with a 4-pin FW400 and a 6-pin FW400 (plus the internal 6-pin FW400 to connect to the motherboard), but those are electrically identical modulo the power pins, so they're really the same sort of device. It had a connection for 4-pin motherboard power, which because that has a 12V rail, was one of the few devices to power both sides of the hub.no-name 3-port device:
And yes, I'm still using FireWire, but only for the same specific purposes I used it for back in the day. Besides A/V (my HDV roadgeek camcorder, my Canopus ADVC-300 framegrabber and my original iSight), I almost entirely use FireWire for booting and exchanging files with the Power Macs. But it lingers in prosumer A/V applications like recording studios and multicamera security setups, and big multiple-endpoint configurations like that are where FireWire's topology really shows off its flexibility. If you're in that category and also absolutely nucking futs, I spotted this auction for a terrifying 16-port FW800 device in an external PCIe enclosure (not my auction, not affiliated).