Sadly, there is no 3G down here + very (I mean, VERY!) slow GPRS, so while out of home, there is no point on having more than 2 or 3 apps running at the same time (Contacts, phone, music player and ocassionally notes/PDF/etc).
However, when browsing at home I tend to have 5-10 web pages (specially talk.maemo.org), email and communication).
It is true that, when having all this open, receiving a call is almost impossible!