Re:
This is the technique I use:
[youtube]https://www.youtube.com/watch?v=jvvXrlAUUfU[/youtube]
Stand the wheel on the floor, make sure the beads are in the centre "trough" of the rim, then push the tyre around the rim towards floor, then pop the last bit on with my thumbs.
Some tyres are tighter than others, but I can generally get them off without levers too, using a similar technic, where you push the tyre around the rim to create some slack, then rolling the tyre over the rim; if that makes sense.