Cloud-based infrastructure and technologies allowing easy scaling as much as possible
Elastic IP or equivalent;
EC2 instances or equivalent for WebServer and WebApp;
Spring framework;
Spring tcServer;
Hibernate;
PostgreSQL or MySQL (RDS, Xeround);
SimpleDB or another NoSQL technology to log events;
RabbitMQ or Apache AMQP as message broker;
ElasticSearch to allow geoloc queries;
HAProxy;
Hyperic for monitoring;