With the ever-decreasing USB flash memory prices, it might be an interesting idea to create a SATA2-interfaced device that stores information on RAIDed USB memory sticks using nothing more but a RAID storage controller connected to the memory sticks and a regular SATA2 HD connection.
Say you'd want a 10GB drive with relatively good bandwidth, high reliability, low power consumption and absolutely no noise. You could plug 5x 2GB USB flash memory storage devices, like, say, 5 Corsair Voyagers, which would, when RAIDed, give you 10GB of storage... with a 10 year warranty... And you'd get around 90MB/s of read speed (guessing 5x ~18MB/s), and, if all goes well, ~65MB/s of write speed (guessing 5x ~13MB/s)...
If you had such a USB storage RAID device with, say, a total of 8 USB ports, you could plug as much memory as you'd like at any moment. You could even put 8x 4GB thumb drives and go for 32GB of storage with [hallucination] 8x 18MB/s = 144MB/s read and 8x 13MB/s = 104MB/s write speeds! [/hallucination] (16x 2GB would even double this, theoretically)
Would still be a bit expensive, but more scalable. But I was just thinking... And that no noise argument is rather interesting for many situations.
If you're thinking this is just too crazy to be dignified with an answer, just ignore this wacky idea...
It is a good idea, but the problem is simple Flash memory wears out. Fairly quickly at that. With constant (re)-writing they would probably only last a year or two, but in the meantime it would be cool.
I saw something saying a vendor was working on 32GB compact flash, the idea being that you would use one or two of these on a small laptop, in place of the hard disk. I'd have to agree, the concern would then be on the lifetime, but it is an interesting thought. Lot less likely to die in a drop.