What do you use to develop in? Eclipse or ...

I use Eclipse on a Mac Book Pro, with a nexus one usb thethered for testing.

Giro.

IntelliJ Idea using Ant scripts and command line tools (ddms/debugger). Idea 9 has Android integration, but I refuse to rely on any custom build tools partly because I'll be releasing some of my work soon including project files for various environments.

I used to use Eclipse on a PC running Windows XP, I now use Eclipse on the same PC running Ubuntu. Eclipse was quite difficult to set up properly on Ubuntu but now that I've done it, it runs much faster than it did on Windows XP

At the moment, I rely on the Android emulator to test my apps but I plan to get myself a GA phone later in the year.

I use Eclipse as my IDE of choice for all my programming, except Dev C++ for C++ (but I do very little C++ development anyway).

I use IntelliJ Idea 9, but it's not free to use with android. Eclipse is also a good choice though. It's more a preference to what you are used to.

I am a beginner, and only know how to do even the simplest of programming in Eclipse.

i use eclipse on a notebook running windows vista.
works perfect!

I use Eclipse on both my MacBook Pro and Windows 7 PC. I test using an AVD.

I use Eclipse but, for some of my applications whose code I want to optimize and strip, I do the making (from the resources packaging to the signature and zip alignement) outside of Eclipse : you have to realize that Eclipse is a good tool but that you could do all using notepad and the command line tools provided by Google (of course that would certainly cost you more time).