It seem that a lot of developers seem to forget that Sitecore has some excellent logging tools which make their life easier. It also gives you the ability to find out about problems which otherwise appear wjhhen the applications is deployed on your production environment.
You can find the log-files these days under %sitecoreRoot%/data/logs and %sitecoreRoot%/data/audit. All the exceptions including stacktraces which occur will be saved in this logfile. So when your website is down and you see some yellow pages on the website, just download the logfile. You can also do this using the reporting tools in Sitecore to download the logfiles. So you don’t require fysical access to the server.
I also recommend to walk to your log-files during your development. Personally I check the files direct after installing Sitecore(after the first run), when I’ve created a new page/extension and at the end of every day. When you are going to deliver an application in Sitecore to yur test-team, just install the app on a clean machine, when the test-tema is finished, you can run trough the log-files and merge the testresults with the information in the logfiles.
Happy bughunting ;-).