Use the built-in backup tool to make a local backup, then do this:

http://talk.maemo.org/showthread.php?t=59328

It's still funny how no one listens or even considered soldering down USB, the last month has seen a big number of broken USB's, well im done trying to say get it fixed.

It depends on whether you're still in warranty or not, and whether you're capable of doing the soldering. My N900's still in warranty (for another month or so), so I've not done anything yet - once it leaves warranty then I'll get it soldered down more securely.

and maybe it will be to late, an then if it breaks within warranty period, well good luck trying to get a new N900/get it fixed

For those in warranty:
There are a few N900s floating around nokia repair's contractors in the EU. It is advisable to supplement the repair note with a request that you don't want anything other than a repaired/replacement N900.

NB. This is NOT the same as a nokia repair centre, which are retail outlets, licenced by nokia - these will swap your N900 for a symbian device while the mail-order ones are less likely to.

If you're out of warranty:
Learn how to solder, even if it still works!

Guys with warranty have also chance to get E7/N8, sell it, and buy aftermarket N900 for much less = profit, so I understand that some may wait with soldering. Anyway, it saddens me, that in such case, fully working N900 (besides broken usb) is "deactivated" by Nokian "murderous". Judging by popular demand, we may live up to times, when N900 will start becoming *more* expensive (in aftermarket) with every month, instead going otherwise. Especially, that there is still no real competitor.

I have usb problem, can u explain how to solder? i am willing to try!

links in my signature (number 4)

Now what can be done if the USB port is mostly functional - but you have the opposite problem in the making? That is, the outer metal shell is fine, but the inner part with the pins requires fiddling to get a solid connection.

Before you ask, it is out of warranty, by a few months. I've done the searching, just that I see more articles about the outer shell detaching than the inner one being loose.

I think I would carefully desolder whole port (to not damage pads), and replace it with another one, doing it like joerg_rw described some posts ago - basically, resembling design of audio port. Instead of soldering new port to PCB directly, You solder it via wires (may be short or longer ones, depending on preferences), then, You encapsulate port in epoxy putty, taking care to *not* allow it to adhere to PCB (by applying some silicone paste or oil to parts, that may come into touch with epoxy - except USB port itself, of course), case, or any other element - you just want epoxy to get shape fitting into surroundings (case etc), so it's held into place, but doesn't apply *any* forces into PCB.

Such a design is probably the best thing one can achieve - virtually indestructible, and even if, only cables would be damaged, leaving PCB pads intact. In case of another strange damage of USB port, replacing is much more hassle-free - You solder new one to remaining wires, and apply epoxy "shapeshifting" again.

It may sound complicated at the beginning, but idea is quite easy, and I strongly recommend doing so, judging by your circumstances.

/Estel