Google Zeitgeist
Google has a page popularity of various search patterns, including the top 10 gaining queries and the top 10 declining queries.

For the week ending August 9, 1994, the top 10 gaining queries were:

1. mega millions
2. doom 3
3. rick james
4. mary kay letourneau
5. anastasia myskina
6. olympics
7. ralph fiennes
8. quincy carter
9. hurricane alex
10. lindsay lohan

For that same week, the top 10 declining queries were:

1. the village
2. jibjab
3. robert sorrells
4. democratic national convention
5. barack obama
6. jennifer love hewitt
7. alexandra kerry
8. lori hacking
9. big brother
10. amish in the city

Metaspy offers both filtered and unfiltered peeks at the search terms people are using. Here's a sample from the filtered version:

big plus
function and theory of 12v battery charger not shopping online
function and theory of 12v battery charger not shopping online
processed 100% plantago hydrocolloid
dallas 'deep elam'
va funeral
ndc+ programmers reference guide
i like coconuts
food
childrens ability fund

Here's a sample from the non-filtered version:

rc car racing
jebediah
isaac asimov biography
s
refurbished ibook
international travel greece
ship lawn mower to apo
"curtain hooks"
jobs in fine dinning restaurant in usa
lethbridge, alberta dancing girls

Oh no! Isaac Asimov! And dancing girls!