Some phone drama this week: my 2 month old Samsung Captivate stopped making noise. I could still talk to callers but it didn't ring, alarms didn't sound, and silent reminders aren't helpful. Google turned up many people with the same problem but no solution. The big tip was pushing on the speaker :p
Tonight I tightened the screw next to the speaker and so far so good. Hopefully this is a permanent fix. And maybe I can help someone else with the same issue.
ETA: The next day the speaker cut out again. It appears many of these phones have poor speaker connections and there's no fix.