Some MS Windows services have a literal dollar sign ($) when viewed in Windows Services. Most notably are MS SQL databases where the service name is MSSQL$DBNAME.
NOTE: In the above and what follows, "MSSQL" is literal as is the last "$" preceding DBNAME but DBANME itself would be whichever database name is in use on the specific hosts. We have at least one host with 3 separate DBNAMEs.
For Nagios 1.x I'd been able to add monitors by simply escaping...