Tromso to Trondheim?

Everything is possible, although I'd recommend taking a plane. In Norway there are no trains north of Bodø (except a train that goes straight east from Narvik into Sweden).
But you can take a bus from Tromsø to Narvik, then take another one from Narvik to Fauske where you can hop on a train.
You can find bus tables here: http://rp.tromskortet.no/scripts/travelmagic/travelmagicwe.dll
The main station in Tromsø seems to be called Tromsø Prostneset, in Narvik it's Narvik Rutebilstasjonen and in Fauske it's Fauske jernbanest. Train tables: www.nsb.no

About plane: If you book early both www.Norwegian.no and www.sas.no will probably have cheap tickets for direct flights Tromsø-Trondheim. (SAS from NOK 559 one way, Norwegian does not have June tickets available yet but in March from NOK 349+luggage fees).

Hmm, you say the northern most train in Norway stops at Bodo, is there any way to get to Bodo from Tromso?

Also, does the Bodo train have a connection with Trondheim?

You can also go by ship: www.hurtigruten.no but that takes two days. The train from Bodø goes direct to Trondheim, Fauske which was mentioned is the first stop east of Bodø before it turns south.

I found that the Hurtigruten ship was actually cheaper than the bus from Bodo to Tromso. You can take it as far as Bodo, then change to the train. If you book in advance on the train, you can get the MiniPris which can be as low as 199 NOK ($35) anywhere in the country on a single trip.

The ship option sounds great actually, I looked up its schedule and it stops in Trondheim too. Would it be easier just to take the boat from Tromso all the way to Trondheim?

It is certainly a pretty and lovely ride. But expenses can definitely add up once you include cabins or on vessel meals. Not to mention it's by far the slowest option.

That said, i would not trade my Hurtigruten experience for anything

Well, I looked on the website for the ship and it seems nice and all but the one problem is that it takes 4+ days to get to Trondheim. I mean I don't mind waiting 10 hours on a bus or a train but that many days on the boat seems a little much.

Why is it such a special experience?

Also, I'm looking at some of the schedules and the south bound boat starts as far north as Kirkenes and ends in Bergen. Would it be possible to board at Tromso and get off at Trondheim?

It's party tradition. It's party beauty. It's partly shore visits.

By no means do you have to take it from start to finish. I got on in Bodo, and got off in Tromso 24 hours later. There is a point-to-point pricing system so it's not like you have to pay full price to do a small portion.

That's why in post #3 i suggested taking the boat from Tromso to Bodo (Although the boat is longer than bus, it is cheaper and cooler) Then, from Bodo to Trondheim, you can take the train. They have a special night train service with cabins (for the 'wealthy") or reclining pullmen seats.

Hmm okay, I think the boat option sounds the best then, at least until Bodo. I can save on a nights accommodation as well.

Got another question, what the heck is a minipris? In my research I've heard about it being the "cheapest way to travel" in Norway, but don't really understand exactly what it is.

Thanks again for all your help guys, this info is really helpful for planning my trip :)