Peter has mentioned that's there's over 90,000 members of LostCousins. So if each of us just added 100 people from the 1881 census (which is free to view), that would be 9,000,000 names. Because the population of the 1881 census was only 29,707,207 you will see that we would have entered a 1/3 of the number of people in the census, so how many matches would that give you?
I found entering a household was really easy, select the "Add a new Household" from the Search screen, select which Census, and add 7 bits of information. Adding the remaining people in the household is even easier! You only need to add 4 bits of information. I was finding that adding a new household of 5 people was taking about 2 minutes. So to get to that magic number of 100 ancestors added by each of us, would take less than an hour.
Now how's that for a great return on your time?
The moral really is, the more we add the more likely we are to match.