Since devs control whether their apps can be moved to the SD card, you may have been disappointed by the list of movable apps you saw on your HTC EVO using something like App 2 SD. Most of the apps on your phone don't have that coveted "Move to SD Card" option, right?
If your EVO is rooted (and why wouldn't it be?), then you can move any app you want to off the phone's paltry internal storage and on to that 8GB, 16GB, or 32GB microSD card instead.
Now, in many cases, devs actuallly have good reasons for preventing you from moving the app, so don't try to dump everything on your card. Items on the card load after items on the phone and apps will sometimes cause problems when they've been forced to move, so do a Nandroid backup (tutorial here) before you go crazy and start moving a whole bunch of stuff.
Most apps can actually be moved to the card with no problem, despite the dev's wishes, so it's not as risky or scary as it seems. It's also not hard to move something back to the phone. Even so, the standard root disclaimers apply here and as always, please proceed at your own risk (and don't spam the comments or my inbox with pleas for help if you did something you shouldn't have done).
Here's how to move any app to your rooted EVO's SD card:
3. Long press the app you want to move and remove your finger from the screen. After a slight delay, the "Special features" context menu (shown in the screenshot above) will appear.
4. Tap the "Move to SD card" at the bottom of the menu. When the move is complete, you'll receive a confirmation in the notifications area of the EVO's taskbar.
And that's all there is to it. You may want to run the moved app and use it for a bit to make sure everything is working properly before moving other apps; this isn't necessary, but it makes troubleshooting easier since you're confirming that all is well after each app is illicitly moved.