Car, or regular train service from Interlaken are the main options. Train journey time is a little above half an hour and usually cost 8-12 franks. Interlaken has connections to other major Swiss cities.
Charter/Tour buses, taxis, and car rentals are also possibilities. Mysterytours (http://www.interlaken.in) offers some options, as does Fun-rental Interlaken. Only 30 minutes by scooter to Grindelwald from Interlaken.
In summer and early fall, is also possible to hike into Grindelwald from well-marked Bernese Oberland trails, with or without the assistance of gondolas / cable-cars.
