One thing I have noticed, not sure if this is recent or well treaded ground here on HN no doubt, but if you Hover over the "I'm feeling luck" button then leave and hover again, it gives a bunch of different options like "I'm feeling adventurous", I'm Feeling Puzzled, I'm Feeling Curious. I am not sure what changes to the algorithm is made when you use one of those, they do seem to give different results. I am sure it is probably documented someplace but I think it would be nice if they had a drop down menu there instead with perhaps a bit of elaboration. I have tried using different ones when the regular search is giving me pop culture type results due to perhaps ambiguity with the more interesting topic I am searching on.

I always thought a good one would be "And now for something completely Different" that would give you random low ranked results just for fun :)