Java-based Oracle SQL Developer has a plugin module that supports SQL Server. I use it regularly on my Mac. It's free, too.
Update: here's how to install the SQL Server plugin:
* Run SQL Developer
* go to this menu item: Tools/Preferences/Database/Third Party JDBC Drivers
* Click help.
* It will have pointers to the jar files for mysql, sqlserver, etc.
* SQL Server jar file is available here: http://jtds.sourceforge.net