This is great since I use both Heroku and MongoDB. Pardon the self-plug, but I wrote an article a few months ago about using Heroku with external MongoDB servers: http://www.developer.com/lang/rubyrails/article.php/3860616/...

Last year I tried to talk a customer into using Heroku for a medium size web deployment. They didn't go for it, and so we spent a fair bit of money setting up Elastic Load Balancing, EC2s, etc. Unless you expect a zillion users, it just does not make sense to spend the effort on custom deployments. Same positive comment for using high quality VPS hosting where you can expect your hosting company to do frequent incremental backups, proactively repair RAIDs, get VPS instances back on line quickly after hardware failures, etc.

It is a lot of fun setting up servers but the question is whether that is worth being pulled away from application development. Anyway, good news re: MongoHQ being an add-on product.