I'm using Tasker for lots of things, and I still haven't gotten to learning it's variables syntax.
There's a dual State->Wifi Near and an Application context for switching on GPS when certain apps (Weatherbug, outdoor excercise apps, Navigator) are running. It's set to control my wifi activation for when I'm home, AND when certain apps are running. I so love watching my wifi widget flash off as soon as I've shut down Dolphin or YouTube!
I don't have a car cradle yet, but I have a Time context set to enable it on weekday mornings, as well as disable both bluetooth and wifi during my sleep hours. A brief Time context for the weekday mornings and afternoons enable GPS just long enough to wait until I pull into my work building, so that a Location context can shut off bluetooth and wifi while I'm there, and another short Time context allows it's exit task to reactivate bluetooth when I leave. Sort of complex, I suppose, but it uncomplicates my life when I leave the building at lunch for a walk. I already have an installed app for controlling sound volume and selective silencing of ringtones and notification noises, but if I wished to automate these on a schedule I could add it to this context by pushing a few buttons.
The automatic dial "feature" is an embarrassing PIA when it dials by accident, because you touched the screen after ending a call. This is why the phone app should disappear, rather than linger there after you finish a call. Since the Android developers did not see fit to return me to my homescreen after a call ends, I set an Event->Phone Idle context with the task to Go Home. I've also got a context set for blocking specific callers, and am experimenting with one which records incoming calls.
My favorite is one which shuts off my screen fast when I set down my phone. You can set it to respond in many ways for any position which your phone is in, face down or up as well. Since I hate having to keep my thumb busy on web pages just to keep my screen timeout at an efficient setting, I keep my display timeout long, but tasker will shut the screen off in 7 seconds (it won't set it for less than this) when my phone goes down flat. If you need to use your phone while it's laying flat on the table, it can be set to shut off the screen only when it's lying face-down (my case provides a scratch-safe buffer with most surfaces). This was done under a State->Orientation context, and the task can be found under Display.
Tasker is surely a powerful app. However, my cause to be impressed by it is a bit relative. The fact that it's the best available doesn't mean it couldn't, or shouldn't be better. I am particularly stunned that a paid app leaves no option to selectively activate contexts - you can run Tasker with all of them set to "On", but if you want to activate only some of them for any given occasion, you must delete those which you don't currently want to have running - hardly user-friendly for the most expensive app on the Market! Also, although Tasker can do a lot of things, the fact that I can't set it to do just anything which I would be doing with numerous button clicks does annoy me. A long time ago (at least ten years ago) I played with an experimental Windows application which recorded my button clicks, saving them to be run whenever I wished, with no need to study any sort of script-coding syntax! Why this idea never went viral in the user community still baffles me, although it's understandable that the software companies would never promote anything which would end their ability to sell programs and apps!
