Site monitoring service?

Are there any decent ones?

[Compworld]

Are there any decent no charge Internet monitor services?

Thanks,

CompWorld

[netguy]

I use WebTrends to monitor if one of my servers goes down, but as far as analysis, NetMechanic isn't bad. They have a free trial to determine various server performance.

[netmechanic.com...]

[Zaphod Beeblebrox]

I use www.watchmouse.com, but I don't know if hey have an english version. At least they're free.