I've used a lot of software development tools since I first taught myself to program in high school (using Turbo C++ and Windows 3.1 — those were the days). Now I use emacs for quick tasks, but I spend most of my time in:

PyCharm

PyCharm takes a solid minute to start up, but saves me hours when I'm writing Python. Its interactive debugger is fast and solid (far better than Komodo's) and its editor has tons of nice features, like highlighting uninitialized variables and unused imports. If I start using a module without importing it, one keystroke will insert the import at the top of my file (and keep my imports alphabetized!) without leaving my current position in the code. Like any rich IDE, there's no end to the features and keyboard shortcuts I have to learn, but every day I get a little faster with it. It has a nice integrated test-runner, with code-coverage charts, and I hear it has a lot of Django integration features I've yet to try.

PyCharm 30-day free trial — you won't look back.

Git Tower

Dan Crosta says to never use git GUIs, but Tower proves him wrong. It's a fast, pretty GUI, but the killer feature is its "stage chunk" feature. When using git from the commandline, I'm rarely willing to endure the suffering of committing some chunks of changes and leaving others uncommitted. With Git Tower, I do this constantly. I embark on a multi-hour hackathon, dealing with multiple features and bugs, and when everything's working OK, I commit my changes in nicely organized sets of chunks.

Git Tower 30-day trial — you'll forget all you knew about the git command line, and that won't bother you a bit.