Can you get a list of the RUNNING applications on Android for the purpose of activating them?

This may not exactly answer your question, but if you press-and-hold the home button, you should get a list of the most recently-run applications. Pressing any of them will activate the app.

This is built in to (I believe) the launcher, so it is possible that this only applies to stock Android and that it has different behavior on TouchWiz (or whatever skin Samsung put on the Galaxy S phones).

A program like Advanced Task Killer will give you a list of running applications. Long press on one of them pops up a menu, and one of the options there is to switch to the application. You can also customize the long press so that the default action is 'switch to', saving you a menu.

There are lots of reasons why something like a task killer is not something you should be using, but I won't get into all that. I have it on there for the extremely rare occasion that I need to kill a rogue process.

You can also do a search over at App Brain for 'task switchers'. AppSwipe! looks decent, but I've not used it (or any of them).

I usually started an application by inputting the name of the application on the Search Textbox. In my Samsung Spica, there is a dedicated "search button", I can click on the search button to go to the Search Textbox and start typing the first few letters of the apps I want to start; the autocomplete will do the rest and you can click on the application you want to start.

In Android, conceptually all programs are continuous and never halted. When the OS needs to reclaim memory, it pauses the application and asks it to save state; later on, the OS wakes the app up and asks it to load its state. Conceptually, applications never dies; conceptually, all applications are running all the time; Android's Activity life cycle is designed to give this sort of illusion.

The app Smart Taskbar will show you a list of the all tasks(apps) that are currently running on your device and allow you to switch to that app, similar to the native functionality but you are not limited to the 6 most recent apps.

Basically it opens from any screen and also lets you set some shortcuts and widgets and choose from all installed apps (like the app drawer) so you can complete any task from anywhere on your phone without having to go to the home screen first.

There are a bunch of other apps that let you switch between running apps, just search the market for "task switcher."

Sounds like you're overthinking it. Android goes out of it's way to intelligently manage applications and resources. When you leave an app it will generally keep running as long as the resources are available. Long pressing Home and selecting it or just launching the shortcut again should take you right back to the running app.

Theoretically it shouldn't matter if it is still running or not, though -- every app is supposed to save it's state in such a way that if the OS kills it before you come back, it should still be able to launch back to the same state you left it in. This isn't universally applied in programs yet, but it does seem to be much more widespread these days -- presumably because the developers are getting used to the "android way."

I know of two other places in Android to get the list of what's currently running. (This is on my Motorola Droid.)

From the Home screen:

Settings | Applications | Running Services

OR

Settings | Applications | Manage Applications | Running

The views are different; one shows all the services from each app, the other just shows the apps.