logrunner is an AIR application which can be used to debug applications by displaying any log file. This application can filter the log file with comma delimited words without spaces. User can also apply Rules to modify the logs with different colors, bold, italics and font sizes.
This application has been developed primarily keeping adobe's flash, flex and air debugging in mind to keep a watch on the flashlog.txt. But since its just a .txt file am watching, it could just any .txt file that you want to keep a watch.
Since this application is done is AIR, it is cross platform (No OS constraints). Though, I haven't tested it yet on any platform other than mac osx.