Hi,
yes you can run a vary of checks without an Agent on the server you would like to monitor, for example Host availability via Ping, HTTP. DNS, LDAP, IMAP.
You need at least one Agent which runs the checks and you need to create them manually.
To get a full list, please click on "Browse Resources" -> "Platforms" and the a platform. Then please click on "New Platform Service" from the Tools Menu in the upper right corner. From the service type list you get a full list of services you can monitor.
Mirko