I use a single tab for indentation, and too much exposure to Java and the Eclipse default indentation size (4 spaces per tab) made me used to it. I also find it easier to look at python code indented by 4 spaces per tab. Since I also tend to limit line length to 80 chars, 8-spaces tabs would quickly use up precious space.

Linus disagrees: http://lxr.linux.no/linux+v2.6.35.7/Documentation/CodingStyl...

I don't exactly know why, I just find it easier read with 4 spaces. Maybe a subconscious issue about the eyes having to move more with 8 spaces.