Walk to the summit of Cadair Idris 2930 feet/893 metres. Parts of the route are very steep, but once on the shoulder of the mountain, the going is easier. There are several routes, but the closest to Dolgellau takes the so-called Pony Path, and takes about two and a half to three hours to reach the summit.
In July, the town plays host to the annual Sesiwn Fawr (http://www.sesiwnfawr.co....) World Music Festival. With 6 stages, there's something for everyone. It has been announced that Sesiwn Fawr will not take place in 2009 but is expected to return in 2010
Pan for gold in the river at nearby Bontddu. Dolgellau was at the centre of a "gold rush" in the 19th Century and its mines at Clogau and Gwynfynydd were worked on and off right up until the 21st Century. You're extremely unlikely to strike it rich but it can be fun trying.
Walk or cycle along the Mawddach Trail (http://www.mawddachtrail....), a 9 mile stretch of former railway line, that runs along the scenic estuary of the Mawddach river, through Penmaenpool and on to the sea at Morfa Mawddach. From here you can cross the toll bridge to Barmouth.
Walk the Mawddach Way (http://www.mawddachway.co.uk/), a 49k long distance circular footpath walk around the Mawddach Estuary.
Follow one of the 6 Mountain Bike Trails (http://www.mbwales.com/) in the nearby Coed y Brenin Forest. This was the first UK forest to be developed for mountain biking, and there are a range of tracks to suit everyone from families to expert mountain-bikers.