Available with various numbers of sockets (4 and 6 being most common here in Oz) and with build quality ranging from "excellent" to "total junk"; while having enough outlets fitted to the building itself is preferable, these are certainly very convenient.

Of those I've used myself to date, the clear winner by far is Arista's SPB 1; while the usual cheapos have contacts with almost no spring, which become hopelessly loose in maybe 3-10 years (even with inconsequentially light loading), the pair of Aristas I have are both still going strong. (They were originally in use at Mum's office, then I brought them home recently as they were no longer needed there. One now sits under my PC desk, happily delivering the power to a 600/900/1500W [that's 6.25A at 240V on high, so I'm in the clear as long as the other stuff stays under 3.75A] heater - the Omega Altise OMC15E1 I mentioned before (in the 10th post from the start), to be precise - along with the PC, monitor, and a camera battery charger.) I've posted photos of it here.

At the other end of the quality scale, there's HPM and even worse, some "house"-branded models. So on the scale of A to F, where...
  • A = excellent
  • B = good
  • C = fair
  • D = poor
  • E = terrible
  • F = a total failure
...I would grade the Arista an A, the HPM an E, the "Solutions" (more like Problems) an F, and most of the rest would get Ds.

Anyway, to complete the description of the Arista SPB 1: They're very solid (some of the cheaper ones will flex noticeably if you try twisting them), and although I don't have the type of screwdriver needed to get inside, I can tell that the socket contacts are the type with opposing springy "blades" (Clipsal's 413QC Quick Connect surface socket also uses such an arrangement; the only downside is that if you insert/remove a plug with plated pins too many times, it wears the plating off). The attached cord is, as usual, the Australian Standard equivalent of H05VV-F3G1.0, and measures 0.9m long and is quite flexible (although that was, I think, before the trend to stiffer cords for cheapness hit "critical mass"). So, how long do you think they could last? 50 years, perhaps? cool While they don't have extra-wide spacing or any other fancy features (beyond a rocker-type breaker that can be switched off at will, rather than the usual boring "push to reset" form), I'm unlikely to bother gambling on someone else's power-boards just to fit in bulky plug-packs; I'd personally just obtain, or make up, an extension cord of a suitable length. (They're sure to be well-protected with the power-board's circuit breaker on top of the house's, and the quality of the hardware will always be far more important than adding 1 or 2 more contact sets than someone's posted arbitrary limit; my limited experience with ready-made extension cords, for what it's worth, has been OK.)

One problem remains, though: I need more than 2 power-boards, at least until the next major upgrade to the house wiring. When that's solved, I'll post an update (or if any of you have some handy info, add it here).

Now for the general comments
As occasional overloading of them is inevitable, they have to be protected in some fashion. To my knowledge, it works as follows:
  • North America: The unit is equipped with a resettable thermal circuit breaker, like the Australian models (although the American ones are for 15A, with a correspondingly heavier input cord).
  • Continental Europe: They are built to carry the full 16A (with a 1.5mm˛ input cord to suit), with the house circuit breaker being set for 16A or at the very most 20A.
  • United Kingdom: Their's just rely on the required 13A plug fuse, although many fuses are known to be very "forgiving"...
Trouble is, there's a huge loophole in the system - namely, that 2-way adaptors without OCP (and some functionally similar items - such as extension cords with "piggy-back" plugs, and at least in theory the "Y"-cords sometimes used with PCs) are still allowed down under (and 3-way versions in the USA). Combine them with a suitably powerful set of heaters* (or other high-drain appliances) and you can end up with one hot extension cord (especially if you choose a 20A circuit with a less responsive fuse, instead of a modern circuit breaker)... Ironically, though, they would actually be reasonably safe to use downstream of a power-board, despite some of those comical PSAs. grin

*Then again, using more than 2400W of resistance heating would be quite expensive anyway...