You can tear down dilapidated pieces of property and flip the empty property. These are called scrape flips because you scrape the land clean and then sell it.
You would be surprised how often a vacant lot is worth more than the same land with a tumbled-down, old house on it. The house is usually too far gone to repair, so it scares off most buyers. Even bulldozing the home requires getting a permit, having access to some heavy equipment, and then taking the time to do it and haul off the debris. With the right contacts, though, you can subcontract that work for a relatively small sum, or partner with someone who has the equipment.
As with any flip, you will need to know what the going market rate is for similar vacant lots in your general geographic area. There is no point in buying a house and lot for $50,000, spending $5,000 to scrape it, and then having a vacant lot worth $50,000–$60,000. Also, be sure to research local attitudes about knocking down old houses just to build big new ones. Many neighborhoods resent this trend because it destroys the integrity and charm of the area. Local homeowners can become extremely vocal in their opposition, and may even successfully lobby the local government to impose new construction requirements that will make your land unsellable at a profit.