Note that this works with the initial version of The Witcher and may be removed with subsequent patches.

After meditating near a fireplace in order to allocate your skill points, head back to your skill tree and right click on skills currently allocated. A ringing sound should be heard. After closing the skill tree, go to the fireplace and meditate again. The skill will be allocated from the previous spent point(s), but the point(s) will also be ready to be spent again! This gives you infinite skill points to spend at your leisure, but remember -- if this isn't done quickly, the points won't be given back to you to spend a second time (or more).