I usually have always some widget running on the desktop, like the media-player widget, email-widget, calendar-widget, and the 2 widgets to see the IP & gprs-traffic (I've forgotten the name but they are so reliable that you never have to look up the name :-).

Apps without window, which are always running:

* "Recaller"

* OpenWatch ( + bluetooth)


Those Apps which need open windows, I usually close when I don't want to use my N900 anymore (e.g. at night).

I frequently use in parallel:

* Skype (only via wireless LAN, but I always have wireless LAN around - at work and at home)
-> for IM & Phone Calls

* www2sms (everything from now on on wireless & 3G)

* Xournal

* media player

* fmms (I receive my emails via MMS)

* email (If I want to answere an email and I don't have a PC around)

* Fahrplan (I don't have a car, so have to lookup the bus shedual frequently)

* Opera & Maemo's default browser (I always have to compare the speed and usability -- opera is better/faster/more usable but no flash!) (2-3 tabs in opera or 2-3 windows otherwise).

* Other not so frequently used apps:
MStarDict & QStarDict & Wallet

So, I guess, I'm in the range >6 Apps at the same time :-)

regards,
nexus