Tampere
Tampere (Swedish Tammerfors) is the "second city" of Finland.
Going to Helsinki and Turku
Though much traffic there is going towards the suburbs instead of exclusively to Helsinki, Viinikka crossroads is within walking distance from downtown. Go south from the Orthodox Church or the bus station on the east side of the street, then at the intersection cross the street and turn east, and finally turn south after going under the two railroad bridges. There's a bus stop across from a petrol station that gives ample space for a car to stop.
If you're leaving from Hervanta, there's a better option. Walk to the crossroads of Ahvenisjärventie and road # 309 (a.k.a. Ruskontie), it is 15 min walk from the center of Hervanta. There's a deserted 'bus stop' that is an ideal place for hitching. All traffic passing this place goes at least 5km to the crossing of road #309 and motorway #3 (road to Helsinki/Turku), where the suburban traffic almost vanishes.
