I usually run instant messengers, few chat windows, couple of browser windows, ssh in terminal together with vpn connection.

I usually have a few applications running.

Conboy for notes taking, Calendar then possibly browser at the same time waiting in the background.

When going out for a run I have media player and eCoach running at the same time. That is also place where multitasking fails, when N900 tries to get GPS signal before the run, connect to online services and play music at the same time. Annoying new mixes by choked up machine.

I usually keep about 4 apps running. Conversations for texting (i text a lot), web for facebook and things like that, music player and app manager. app manager seems to lagg up my phone A LOT when it is installing an app, but only for 10 seconds ish, hope this can be fixed.
and also the most apps ive multitasked was 32, i tried 33 and my phone turned off.

Thanks VOLT, I couldn't decribe it better. I actually do subscribe each one of your words. I'm just new with N900 and its multitasking feature (though I come from Nokia's World; always Nokia since I have a mobile). This means that I'm usually connected and running the Application Manager (typical maemo.org ones, not others not trustable -after flashing once-) and that really strains many of phone resources. Up to the point that it seems to hang or crashed when, in between, I receive a phone call. It's just annoying and frustrating not being able to answer adequately, when for me this is the first and main functionality of my N900 (otherwise I'd use a tablet or a desktop PC): slow work, full of background noise, black screen with no possibility to close any running application, .... Really, this is not a phone sometimes, it might be the best multitasking device in the world, but not a smartphone. And what to say about the time the screen spends spinning and deciding by itself about portrait or landscape mode before showing the touchable buttons to pick the call or to reject it. I think the phone call functionality must work perfectly over all the rest of functionalities (if not, I'll go for an iPhone ).

It's a very good idea what volt suggests: to keep and reserve some memory slot for this phone call functionality to work properly and in real time.

I do hope excitedly to have such an improvement in next OS updates. Meanwhile, I will not be a fan of your multitasking feature. It's very difficult for me to spread the goodness of my N900 while this phone-call functionality does not match my basic needs for a smartphone.

Apps open occasionally in meetings:
email
conversations
browser
calendar
xjournal or an texteditor

I hit 1-3 as this is for meeting times

normaly I got conversations & calendar open

I guess calls do not count...

for performance:

If you want to use your phone don't take a picture ahead as trackerd or thumbnailer will eat your device.
It does not matter how many apps are open, if only one of it likes to hug the mmc you are done with it... no response for minutes... so it is not only the RAM as many people claim, sure low amount of RAM and constantly swapping makes it worse!
I guess if one of us is looking into hardware details someone will come up with a pretty good idea for a hardware-setup to prevent the device from freezing while transferring files to ext. SD... improve the data pipes!

Well, now that the actual polling has ended, time to get down to the real skinny

These days, I use the N900 a lot as a reader.

I have three or so programs open:

FBreader, Zim, and a browser.

I am constantly switching from FBreader to Zim to take notes on what I am reading. I really wish there was an easy way to go to the last thing open like Alt Tab does. Ctrl Bksp doesn't do it adequately, because then I have to choose what program to go to. I already know -- I usually want to go direct to Zim and then direct to FBreader.

Once in awhile I want to look up a word (or place) mentioned in FBreader, so I typically go to the browser for that.

Sometimes I open a map program so I can (where's Frodo? Where's Ayla? Where's the killer?) follow the action.

I hope that the Kindle sometime makes such switching easy. Or the N900. An easier Alt-Tab feature (back to the last window you used) would be great.

Lol i m located in the 2.70% ...

i usually have fbreader constantly open in the background, so i can quickly get back to my book during dull moments. other than that, i'm a bit wary of battery life and the time taken to swap the phone app in, so i tend not to multitask too much

I use to have 3 to 5 windows opened. Browser, mails, xTerm...I use to avoid having more than that as I a only one brain ;-)

As many others have already pointed out something similar, I too tend to close any unused window to save resources. It's quite annoying when the device gets unresponsive, especially when you try to answer a phone call.

Also, while not a separate window, I'm mostly online on several accounts. I feel having this ability is true multitasking, since surprisingly many devices are not able to do it in the background. However, this seems to be very resource hungry. When moving between 3G and Wi-Fi, the reconnecting makes the device almost unresponsive for fairly long time and Bluetooth headphone becomes useless during that time.

But despite of these shortcomings, the N900 has the best multitasking of any hand-held device I have ever used. I just hope that the future MeeGo products would have more RAM and processing power, so that unresponsiveness would be a thing of the past. Also, I think volt had some great ideas in this post.