Not too long ago, we were approached by a new client. They were an online auction company and had written software using PHP and MySQL. Fortunately for them, their company was taking off in Australia. Unfortunately for them, their application wasn't well written and didn't scale to meet their client load.
The simple short term solution was to throw more hardware at the problem. Overnight, we migrated their application to the cloud and distributed the system from one server to seven servers. This solved the scalability problem.
Over time, we worked with the client to make incremental improvements in the software so that they could support a larger client base with reduced hardware overhead.