I'm working on a simple game for iPhone based on cocos2d. Yesterday I installed it on my old iPhone3G and it was veeeeeeeery slow. After a lot of refactoring I found a NSLog call inside my game loop. It basically logged all the collision detection of the player with all the tiles in the map. After removing that it's even faster then before. So, if you want to log something, do it, but remember to remove all these logging calls later.
In the last weeks I played a lot with CouchDB and I love it. I always used it from ruby but yesterday I tried to use it with flex. I started a new Actionscript project called CouchDB Flex, you can browse the source from github. The implementation is inspired by couchrest, but it's asynchronous because I use URLLoader internally. Since the flash player doesn't support the PUT and DELETE HTTP methods, you must create an AIR project if you want to try the library. You can find a compiled swc here, put it in your libs folder and you are ready to go. Here a small example, but it's still in development, and a lot of functionality are not implemented yet.
Cucumber is a great tool I usually use for BDD in my ruby projects, but yesterday I tried it with Flex, and it was very enjoyable. Here a little example on how to test Flex applications with Cucumber.
If you run a rails application on multiple servers behind a load balancer, almost every time you make a request you have a response from a different host. If you want to know which host has sent back the response, you can use a middleware that adds the hostname in the page title of each request.