I moved my blog and other sites to a hosting company called www.m6.net about 4 months ago.
They quote 99.9% uptime
Well my own monitoring shows a lot less than that - infact how often have you found this site down? My monitoring over the last 20 hours shows it down for 168 minutes.
Well I decided that my single monitoring solution is no good since it may be my ISP that is down or maybe one of their network partners. I found a free service called MonTastic that provides a free service to monitor up to 100 sites for free.
I am still at a testing stage but I would like to recommend their service. They have an RSS feed per account so you can use this to determine the uptime/downtime of your site - but I would like more.
I have offered to write a Windows Vista gadget to display the site status - we will see if they accept.
Check it out at http://www.montastic.com/
ps: I would be very cautious of hosting with www.m6.net