The internet is a great resource for information but it does not replace the hard work of hands on research. The databases are limited to the information which has been inputted. Also, the passion (obsession) that you have in discovering your family drives you to look past misspelled words, illegible handwriting names and seemingly inconsequential details.
For example, I am constantly disappointed with www.ancestry.com. I have searched unsuccessfully for names in their database which I found on my own at archives and libraries. The handwriting seems to throw the site. Dobson is seen as Dadson. Napoleon becomes Nopson. Warren is recorded as Worn. It is a plus that you can view the actual census pages on ancestry.com but you can't rely on the site to find the names.
To get around that go to www.familysearch.org. It is the free web site of the Family History Library's database, a project of the Church of Jesus Christ of Latter-Day Saints (Mormons). The entire 1880 census of the United States is available there. What make this so great is that the names you search don't have to be spelled correctly in order to find them. Once you find an individual, there is a link to a corresponding census page at ancestry.com. The only hitch is that you must be a paid subscriber of ancestry. com to view the page.
The most helpful site online for me has been the Tennessee site on the www.usgenweb.org page. The website is free unlike ancestry.com and manned by dedicated volunteers. Unfortunately, all states are not equal. The Tennessee site is so superior to the Mississippi page, the two pages I visit the most. Natalie Huntley has done a superb job for the counties of Dyer, Crockett, Gibson, and Haywood as coordinator even though she lives in Illinois. I recommend the site to anyone looking for data in those counties of Tennessee.
Aside from databases, the most valuable commodity of the internet in genealogy research is the connecting of like-minded individuals. Some of these people have been relatives I would never have met otherwise, distant in miles as well as on my family tree. Finding and communicating with these living cousins has been as exciting as finding obscure ancestors. And it would never have happened without the internet.