Where I work at the moment I am luck enough to be working in a team of developers who are working with Agile/Scrum/Xp, and we were also lucky enough to have ThoughtWorks (Martin Fowlers company) come in and teach us a few things. One of the things I like was Inversion Of Control / Dependency Injection, which is all about moving the creation of object references out of constructors/properties into a central container.
I liked this so much I wrote an article about, which you can read using this link.
Its quite an interesting subject once you get into it. Hope this helps even if it just shows you how to think a little differently.