Just to recommend a hostel that I stayed at in San Jose, Costa Rica - the Molino Rojo Hotel - www.molinorojohostel.com. It was everything that I needed from a hostel - clean, organised and well-equipped. Their parties are awesome too.
As they are a new hostel, they aren't high up in google and aren't in any guide books, but they are really well-located on the main avenue Paseo Colon.
Check them out - www.molinorojohostel.com