The Spider Cut is not really a cut - it's more of a flourish. To see a video tutorial (no speaking) go to this site: http://www.youtube.com/watch?v=SLtkhERny0U
(this is NOT by me)
I give credit to Mikkel Samuelsen, and twin brothers Dan and Dave Buck for this.

I will show step by step photos and explanations. Good luck!

Hint: It's easier than it looks (not saying too much but still...)

Step 1: Grip

How you hold the deck to start.

Picture 1: Ensure you hold the deck EXACTLY in this position.
Picture 2: You should be able to do that.
Picture 3: The starting grip.

By the way, look for cards that fit your hands. It's much easier for learning. When you are done, you can use larger cards (like title pic).

Step 2: First Pull

Picture 1: Lift top third like shown.
Picture 2: Lift middle third in a zig zag. Note bottom third is cluched between left index and pinkie. Also note it is the 6 of hearts.
Picture 3: Swing bottom third away (you can just see a bit in the photo) and place left thumb on the middle third.
Picture 4: Split the middle in half. Now there are 4 parts (looks like original three but this one is the 2 of hearts). Other part is still barely seen (still between the two fingers).
Picture 5: Swing 3rd part (from the top) towards you. Note the 2 of hearts is BELOW the 2 of spades.
Picture 6: Swing right hand away from you to swing the cards even further out. Also note that I'm pushing the 10 of diamonds (only one card) with my right index, pivoting on my right middle.
Picture 7: Note that the 2 of hearts is ABOVE of the 2 of spades. The finished First Pull. If you have come this far then you're doing well.

Step 3: Second Pull

Picture 1: Rotate right hand inwards and allow left thumb to contact top card.
Picture 2: Back view. Note my right hand ring finger is not yet touching the 2 of spades. The next picture is quite difficult to see so I will explain now. Your right ring finger touches the corner of the 2 of spades pack (or whatever it happens to be) and transfers it to the left pinkie.
Picture 3: Hard to see but you can see the ring finger has moved. Pivot the transfer on the left thumb.
Picture 4: Transferred the 2 of spades but 10 of diamonds is still touching left thumb, and right ring finger is still touching the 2 of spades.
Picture 5: 10 of diamonds back to original position and right ring finger has released the 2 of spades.
Picture 6: Elongate by pivoting on your fingers. Second pull complete.

Step 4: Collapse

Picture 1: Swivel 2 of hearts pack onto the 6 of hearts pack.
Picture 2: Swivel 2 of spades pack onto 2 of hearts pack.
Picture 3: Swivel 10 of diamonds back onto the original pack and collapse the new 10 of diamonds pack onto the 2 of spades pack.
Picture 4: Square the cards up.

Step 5: Conclusion

If you completed this then some news:
GOOD NEWS: Good job. That wasn't easy.
BAD NEWS: This is one of the more basic card flourishes in the world.

Improvements:
Firstly, it looks better with the backs up (I think). I only did it face up because it was easier to explain.
Try zig-zagging simultaneously at the start. Much more impressive.
I can do this in under 4 seconds. Pros can do it in less time. If you try to get it faster, prepare for a lot of dropping.

N.B. This 'cut' doesn't change the order so it can be used as a false cut.

Good Luck!