http://www.nycourts.gov/courts/nyc/smallclaims/general.shtml
It is for New York City, but you can navigate around to find the appropriate court for your juristiction.

I could not find anything that mentioned estate planning, probate, or wills. Here are the basic requirements from that website:

In addition to the Civil division of the Court, and the Housing Part, the Civil Court of the City of New York has a Small Claims Part. The Small Claims Part is a simple, inexpensive and informal court where people can sue for money without a lawyer. A claimant or defendant may hire an attorney if they choose to do so, but it is not necessary.

The Small Claims Court has monetary jurisdiction up to $5,000.00. Claims for more than $5,000.00 may not be brought in Small Claims Court. They must be started in the Civil Part of the court or in a different court. A claim for damages for more than $5,000.00 cannot be “split” into two or more claims to meet the $5,000.00 limit (that is, bringing one $5,000.00 claim and another $1,500.00 claim to recover damages for $6,500.00).

The kinds of cases filed in the Small Claims Court vary, but a case must seek money only. For example, a suit cannot be brought in Small Claims Court to force a person or business to fix a damaged item, fulfill a promise made in an advertisement, or seek money for pain and suffering. Some of the kinds of cases most often filed in the Small Claims Court include the following:
1. Damage caused to automobiles, other personal property, real property or person.
2. Failure to provide proper repairs, services, merchandise, or goods.
3. Failure to return security, property, a deposit, or money loaned.
4. Failure to pay for services rendered, salary, an insurance claim, rent, commissions, or for goods sold and delivered.
5. Breach of lease, contract, warranty or agreement.
6. Loss of luggage, property, time from work, or use of property.
7. Bounced or stopped check.

Cases brought in Small Claims Court are automatically placed on the court’s evening calendar so that most people do not have to miss work to bring their lawsuits. There are daytime hours available as well, for people who cannot come in the evening. Small Claims Court cases are mostly decided by volunteer Arbitrators. However, either party may choose to have the case heard by a Civil Court Judge.

The Small Claims Court may not be used by a claimant to harass another party. Where a claimant repeatedly unsuccessfully brings the same claim against a defendant, the claimant might end up with a court order denying him or her the right to use the Small Claims Court to prosecute the claim.