Do you have a brick wall ancestor? I think everyone who is serious about researching their family has at least one. Have you thought about contacting the Historical Society in the area where your ancestor lived? Many towns and villages have one, but even if they don't, there is probably one that covers the county, or maybe several surrounding counties. Many have a website which should tell you what holdings the society has and its research policy. You can do a Google search for (town or county) (state) + historical society to find one in your area of interest.
These local historical societies can be a gold mine of information for the genealogist, much of which has probably never been put on-line. A few basic items of interest may include an Obituary File (some of these societies have been cutting obits out of the local paper for years!), Cemetery File, Marriage File, and Family File, which may include family group sheets and letters from others researching the same name. But, don't forget, that they may have one-of-a-kind resources such as ledger books from local businesses; diaries, journals, and scrapbooks; and family papers, including genealogies, letters, and photographs, to name a few. The members themselves may be a virtual wealth of information as some may have lived in the area their entire lives and be very knowledgeable about local history and the people who have lived there.
Keep in mind that these societies are run entirely by volunteers. That said, most are willing to do at least look-ups of the files and some will do an in-depth research of the entire holdings of the society. A few will do a basic search for just a stamped, self-addressed envelope (SASE), which you should ALWAYS send when writing to a society or individual for genealogical purposes. Most will charge anywhere from $5 - $25 or more, depending on what research they are willing to do and the size of the holdings. Even if they do not say that there is a charge, sending a donation of $5 - $25 will always be appreciated, and should be common practice for genealogists.
My personal experience with sending a query to local historical societies has shown that they are usually very prompt in replying; but again, remember that these are volunteers, so be patient if you don't hear from them right away.
If there is an area where your ancestors lived for many years, you may want to consider joining the local society, even if you don't live in the area. For a small yearly membership fee, you may get great benefits from being a member, which could include discounts on publications sold by the society, a monthly or quarterly newsletter (in which you may be able to place a query about your particular ancestor) and a discount on the research fee.
Try contacting the historical society in the areas where your ancestors lived. You may be pleasantly surprised at the information you glean!