There are two ways around that problem, and I have done it before. Please note, this will definitely void the warranty on your motherboard, so proceed at your own risk.
If you look around at different PCI-e slots, especially shorter ones, you'll notice that some are what you would call, 'open ended'. In other words, the back side of the slot is cleared out, and would allow a longer card in, although it will hang off the end and only be supported by the front of the card and the retaining screw. If your x1 slot is not open ended, VERY CAREFUL work with a dremel and an exacto knife can remove that back piece so that you can fit a longer card in there. This shows the net result, but obviously, again, BE CAREFUL.
http://blog.zorinaq.com/?e=53
Another solution is that they do make what is called a 'flexible riser' and sell those in various places (eBay, newegg, etc), what it is - a pci-e hard piece like what you would find on the bottom of your pci-e card with the metal traces in various sizes from 1x to 16x, leading to a ribbon cable, which terminates in a pci-e plastic slot which clips to the bottom of the card. You can then mount the card in any open slot where the mobo wouldn't interfere. So - if you have an m-atx board in a full atx case, you can mount the card in the bottom slots, and run the cable to any open pci-e slot. Nice thing is no voiding the warranty, but you have to buy the adapter.
For those saying that the bandwidth isn't sufficient, that isn't true if it's being used for offloading CPU work - such as bitcoin mining or folding@home. Many people have been more than successful doing that on an x1 slot.