By Bus Or Train
There are also buses and trains that will take you to Atlantic City, which is approximately 20 minutes away by car. The buses that run from China Town in Philadelphia take you to Atlantic City and from Atlantic City, the buses will then take you to your specific New Jersey Shore Location. There is an Ocean City Transportation Center located on 10th Street and Haven Avenue that drops off and picks up.
By car
Most visitors arrive by car via the Garden State Parkway southbound exits 30 or 25, or northbound exits 25 & 29 which can be reached from the New Jersey Turnpike exit 11 or the Atlantic City Expressway US Route 42 exit 7s. There are bridges at 34th Street and 9th Street that provide access into town. You may see several orange signs which indicate that the 9th street bridge is closed, but I assure you it is always open, so feel free to take that exit. There is a third bridge on the northern end of the island as well which links it to Somers Point, Longport, Margate, Ventnor, and Atlantic City.
During the summer season, parking in Ocean City can be expensive. The general rule is the closer you are to the ocean and/or to 9th Street, the more expensive it is. Depending on where you park on the island, it can be as cheap as 50 cents or as expensive as 15 dollars. If you don't mind a small walk, you can find cheap parking at the OC bus station, which is close to the 9th Street bridge and next to the McDonalds. As of Sept 2007, it's 25 cents for 2 hours.
There are some spots around the city, for example on Wesley on the South side of 9th street, where there is free all day or night parking. This is usually used by year round residents to park, but if you get lucky you may find a spot only a few blocks from the boardwalk. Be careful though, many of these areas have time restrictions, such as a 2 hour limit between 9AM and 6PM. In front of the post office it's 15 mins, and they really do enforce that!