Are there any MySQL monitoring suites/tools built to use on systems such as Amazon RDS where you do not have system access? Looking for something beyond custom tools (nagios, zenoss, ganglia, hyperic) and more like MySQL Enterprise Monitor, MONyog, and DBTuna.
You could try MONyog MySQL Monitor and Advisor from http://www.webyog.com.
Two that I can recommend most are Percona's PMM and Shattered Silicon's SSM (fork of PMM v1). Both support monitoring of remote database systems, and SSM has a few features that make it slightly better at monitoring RDS instances because it supports query data extraction from RDS via slow log.
PMM only supports query data extraction from performance_schema, which unfortunately doesn't cover information about queries that run as prepared statements, which can be quite a crippling drawback depending on how the application implements it's query execution.
Disclosure: I work with the maintainers of the SSM fork of PMM1