In a comparison of Google docs and Microsoft Live Office comment 10 by Jrome describes the Google docs speadsheet fill operation and the function "=googlelookup"
You can populate a list of cells by entering a few values and then drag the selection out and have the application guess what you want and fill the cells with the guess. Often this means entering 1 then 2 and having the application continue the series. The Google docs spreadsheet function can fill in car names, cities chemical elements etc.
The "=googlelookup" function can access databases to populate lookup queries.
e.g. you can fill a list with planet names and use the lookup function to list data on them - here is a list of soem of the things you can find
Chemical Elements (like "Helium")
find atomic number, discovered by, atomic weight
Stars (like "Betelgeuse")
find constellation, distance, mass, temperature
Planets (like "Saturn")
find number of moons, length of day, distance from sun, atmosphere
Dinosaurs (like "Velociraptor"): height, weight, when it lived
Here is an example I prepared earlier to find the length of day on planets
1. Create a Google Spreadsheet
2. Type "mercury" in A2
3. type "venus" " in A3
4 Select A2:A3 and, while holding the Ctrl key, expand your selection down to A10
See the list of planets appear from a2 to a7
5. Type "length of day in B2 and copy b2 into cells b3 to b10
6. type "=googlelookup(A2; B2)" in C2
see the length of day appear in c2
7 copy cell c2 to cellls c3 to c10
see the list of planet day lengths appear
Here is a list of Google spreadsheet functions