[biaxident]

I've currently got a few small apps on Heroku and am considering moving some larger ones over. But the "Heroku | Welcome to your new app!" is very worrying.

Custom error pages for these kinds of errors would be very useful.

[iampims]

It took Google App Engine two years to add the option to specify a custom error page for server errors and over quota errors. Hopefully that'll come soon for Heroku as well…

[sync]

It will. Currently in private beta, heroku will render an iframe pointed to an arbitrary url hosted externally (say, on S3.)