acb_ - Replmon can be found in the Windows 2003 Support Tools - On the CD look for the Support directory. You can also find it on the XPSP2 Support tools, I would stick with the Windows 2003 one though.
Replmon concentrates on AD replication, but you can do a whole load of other things like checking the GPOs' status and Forcing replication between replication partners.
Ultrasound though is available by separate download from MS and is for monitoring FRS replication, so Sysvol stuff (GPO's, Logon Scripts, Security Templates), and DFS Stuff......It is a bit of a beast though and requires it's own database (SQL or MSDE). For a snapshot of the FRS replication info you can use Sonar which is a Resource kit tool that is also available for separate Download from MS, but it does provide a slew of information and no documentation which is handy . But it can quickly tell you if you have issues with replication, but you need to match up the refresh rate with the times between your replication windows for it to be useful.........
And from memory there are some scripts in the Branch Office deployment guide from Microsoft to help actually monitor some of this stuff.
HTH
P
