I don't know about you but I like loose coupling. Being able to code against abstractions is great, I can be TDD and focus on SRP and proper SoC. Maintenance and extensibility become much easier and code is visibly cleaner. There are tools out there that help me do this currently such as various mock frameworks, IoC containers and ESBs but I though I would introduce a couple of relative new comers to the scene that can help loosen things up a bit.
A few months (maybe years ago I get up an abstraction of the IoC containers I use (Spring.Net, Castle, StructureMap and Unity) so I didn't have to remember all the different semantics for each container for each contract/project I worked on. Well a few months ago M$ came up with the Common Service Locator. It is a good idea. I like it and may replace my abstraction with this soon (only for the sake of people maintaining my code). If you are a contractor/consultant or use various IoC libraries then this could be a godsend. IoC is a crucial part of my work and many of the patterns I use are very hard to implement without even a basic IoC container. this will hopefully break down some barriers for new comers who cant decide what to start with.
MEF is the Managed Extensibility Framework which allows post deployment extensions. Think about that; it allows me to have hooks in my application so that later on I, or a third party can easily extend the framework, like an improved way of bolting on Resharper to VS or as Glenn mention in this video like can be done in World of Warcraft with various plug ins. MEF is in its 4th release as of this week. Check it out. it has a kick ass team working on it (Glenn and Hammet both get 2 thumbs up from me).
Live and code free.. be a hippie code, get loose man...
Some existing tools and libraries I use and recommend are:
Mock Framework: RhinoMocks