If you've been reading much of my blog, you know that most of my research up to this point has focused pretty much in two areas, Northwest/Northcentral Ohio and Northeast Indiana. I consider myself pretty fortunate that my Indiana research is almost exclusively limited to DeKalb County. In my opinion it makes the process so much easier simply because of the incredible wealth of resources that are available to me and many of them are free! I have listed below just a few of the links that I use in my research.
Archive.org has been a great resource for finding historical texts that are online. (The link takes you to a search for DeKalb County Indiana resources.)
The GenWeb page for DeKalb County is well maintained and on several occasions has pointed me to the source records that I need.
The Indiana County History Preservation Society is a page that I have used only a few times, but it is a good resource for general county history.
The Willennar Genealogy Center has several resources available online and if you are local to DeKalb County, it is a resource that you don't want to miss!
And of course, no list of resources would be complete without mentioning the FamilySearch.org Wiki!
This list is by no means a comprehensive list of the resources that I have used, but it should give you plenty of places to start and will definitely lead you to others.