Unless you've just moved into town, you probably know your own town pretty well.
Well enough, in fact, to set a nice campaign there. Obviously, this works best with a campaign set in the present, and not so well with a sword and sorcery adventure. But any genre can work. For example, a post-apocalyptic setting could use your town as it might exist in the far future. The sword and sorcery adventure could use a fantasy version of your town.
The important thing is that using your own town lets you use all your knowledge of the place as a basis for running a campaign. You don't need to wonder if the town has a public park near the town hall, you know already (or can find out by taking a drive by the town hall).
Some research will be necessary, even though you know your own hometown. You'll want to dig up plenty of adventure hooks and interesting tidbits to interest your players. Don't worry if you think that your hometown is too boring, every town has its haunted houses, mysterious history, and eerie happenings.
Your local library is a great place to start. No matter how small your town, someone has probably compiled historical memoirs from its history. This will give you a sense of the town's history, which is important even for campaigns set in the present day. Current events derive from what has happened before.
You'll also find the most surprising information online. For example, those collections of memoirs may have been converted into electronic form and put on a web site. Or someone may have already done some research and created a list of mysterious disappearances (or whatever) in your area.
The information will often be organized by state. For example, Forgotten Ohio is a must see resource for setting campaigns in Ohio. It catalogs interesting and sometimes creepy areas of the state, including towns that used to exist but no longer do.
Haunted Places is a site that lists current hauntings by state. There isn't a huge amount there for some states, but you might get lucky.
The blueprints for buildings are generally available through the county courthouse. These are probably not available online, and are often in unwieldy form, but you can look at them there and take digital pictures to capture them. Later you can transcribe them, and change them as needed, into your own mapping program or just onto graph paper.
Don't forget your local newspapers! You can often find odd facts that seem harmless enough, but can be woven into a campaign by an inventive GM. For example, a time capsule was unexpectedly found in the wreckage of a building being torn down. The capsule was taken to a safe place to be opened. A creepy horror game could start an entire campaign from that one event.
Setting a campaign in your home town does add some difficulties.
For one, you'll be playing as NPCs people you know. You might be fine with this, or you might not be. Keep it in mind in your planning stages.
For another, I find that I feel a stronger responsibility to research when the action is set in a place I know personally. I have no problem making up New York City as I go along, but set the action in my own town and all of a sudden I start wanting every detail to be accurate.
If you are comfortable NPCing people you know, and can avoid the temptation to make everything 100% accurate, setting a campaign in your home town will probably be great fun for you and your players.