Keeping up with modern development tools and techniques is almost a full time job in itself. Here are some of the ways that I keep current.
The Frontier developers meetup isn't language- or platform-specific, so at each meeting you have the opportunity to either contribute an expert opinion or learn something outside your comfort zone. The Boulder/Denver New Tech Meetup isn't solely about software, but it does bring start-ups and established businesses to talk about the new technology that they're working with and a mostly techy audience to meet and great the presenters with questions, critiques and congrats.
Two almost ubiquitous developer destinations are Stack Overflow for Q&A and GitHub for source hosting and collaboration. I contribute to both when I can, but I've learned a lot from reading other people's code and solutions to problems.
Books written for a rapidly evolving field like software tend to have a short lifespan, but the best books can teach methods or share insights to be applied regardless of the language that you're using or the situation that you're in.
I think most developers have heard of Design Patterns by the "Gang of Four", and the majority of the patterns described in this book are still relevant. Even if you haven't read the book before, several of the patterns will be familiar and given new names and possible applications. This book opens new doors to thinking about code at a higher level of abstraction, or at least appreciating it more. I haven't actually read the original book, but I have gone through a derivative workbook for Java called Design Patterns Java Workbook, which gives concrete examples for each of the patterns described.
The big blue book of Domain Driven Design by Eric Evans also deals with patterns, but in addition to patterns in code, it deals with the patterns in organizing the complex relationships that are required to build sophisticated software. It's pretty dense and will almost certainly take multiple readings to fully grasp most of the concepts, but this book is held in high esteem for good reason.
Programming Collective Intelligence by Toby Segaran uses examples written in the almost magical Python to make an interesting exploration into concepts that are too often hidden behind dry writing.
When I was considering how I wanted to change the trajectory of my career in software, I found The Passionate Programmer by Chad Fowler to be useful on a number of levels. From considering what technologies to learn or ignore, to figuring out what aspect of software development I actually find fulfilling, there's a lot here to like and use.
37 Signals are all about opinionated software development and products and their second book is no different. More or less a successor to Getting Real, Rework succinctly explores the 37 Signals way of running a business. It's sure to give you plenty of ideas about shaking things up and changing them for the better.
The voice of the modern development community, always changing and moving forward in so many directions at once. This is a selection of the development blogs that I've been reading that I've learned a thing or two from recently or over the years. You can also check out specific articles I've found interesting on Google Reader.