Stylus for almost everything, fingernail for the rest if I can't be bothered to take the stylus out. I never use my skin to touch the screen.
And I've had N900 for over 14 months and never once put the stylus in my mouth (I can't even imagine what's on it), nor have I ever lost it.
As others have said, being right-handed and using fingers is not easy. Most pop-up menus appear to the right of the touch, which means your finger blocks it. Using left hand's fingers also tends to cover the light sensor which makes the screen go dim. So using the stylus seems better for both kinds of people.
Yep, I had a real need for the stylus today, but I'm not going to use it until I put a screen protector on. One thing about Xournal though is, I was hoping that it would have text writing support, couldn't find it so far.
On the bottom toolbar in Xournal you can select the "Letter" icon, then you tap a spot on the page and you use your keyboard to type and it then shows up as text on the screen, if that is what you are looking for.
Very important for me especially with sweaty hands on days and nights...
I am left handed so N900 stays on my right hand while I tap with stylus on the left. I chew the bottom while typing with both hands. I almost lost it one day, but still keep the same stylus for about a year...
I'd be lost with a capacitive screen ... for the most part I use the flat of my nail for scrolling ... and regularly use my nail for clicking small links ... and my stylus is taken out for a good number of programmes ...
... MyPaint would be pointless without a stylus & a resistive screen ... with the two it's just like drawing ... without it's like very primative cave painting ... (just have a look at the iphone MyPaint app to see the difference in capability!)
And Angry Birds, Airport, Marbles, Tetris & card games are all easier with a stylus!
If (when) I decide that I need a new phone I'm going to have to keep my n900 for drawing if nothing else as I doubt any future phone will have the same capabilities ...
My top applications are SunVox and MyPaint so the stylus is extremely important. I wouldn't find Angry Birds as engaging without stylus control. I basically use the stylus for everything except phone calls on-the-go. I'll be happily with the N900 until the next device comes along that offers a comparable keyboard and stylus.