Airbrak collects error messages from Ruby on Rails (and others via unofficial plugins) apps and collects them for review. Looks interesting. Starts at $5/month up to 4 projects, 4 users, 15 errors per minute.
Interesting article comparing Rackspace and AWS performance when applying high frequency trading strategies against 10 years of archive data. Rackspace io kicks ass, CPU slightly ahead.
A howto on setting up monit on an Ubuntu server. Fairly simple and straightforward. Includes basic info on customising alerts and so on.
BrandsEye is an online reputation monitoring tool from Quirk. Quirk are a Cape Town based online media company. ORM is monitoring what people are saying and how they perceive your brand online, in an automated way.
aql offer an email to SMS service and offer a link to nagios server monitoring.
ipipi.com is an SMS gateway service. You can send messages online, via email, etc.
TextMagic is a global sms delivery service. You can delivery texts via email, gateways, their own windows app, etc.
filtrbox allows you to manage all your incoming "content". It's called "business grade content monitoring for professionals and SMBs". It watches for relevant stuff, and delivers it in a single, simple format. It's currently free (Mar 2008).
monit is a utility for managing and monitoring, processes, files, directories and devices on a UNIX system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations.