I've decided to share my experience I've had with a silicon case I bought off Amazon. This is the third case I've tried, and by far, is the best.
Other cases I've tried has been two parts in hard plastic, with small circa 2mm "arms" that was suppose to grip in between the screen and keyboard.
The result of this, was that when I eventually dropped my beloved N900, the case sort of exploded and on the ground was the phone not protected by the cover anymore.

Searching Amazon, I finally found the case with short and describing name: NOKIA N900 SILICON SKIN CASE - BLACK, WITH SCREEN PROTECTOR PART OF THE QUBITS ACCESSORIES RANGE

What makes THIS case the best, is that it is silicon, so it actually absorbs the force the impact if dropped AND the two caseparts slide together so they can't come off accidentally.
Funny thing is that the description of the case, dosen't even mention the the option of them sliding together, so it came as a surprise when I got it.




The "rails" that slide together, making sure the cover stays on, even if dropped... trust me, it works


The hole for the micro USB is a bit cramped, some 3rd party cables might not fit.
The cable that comes with the N900 and the retractable one, pictured and linked further down, does though.



Seems like the people who made this cover, only had the measurements and pictures of the N900, and therefore mistook the IR port for a button
A hobby knife should do the trick.


Other covers I've had, didn't make room for the little hole under the "kickstand", so you couldn't get your nail under it, this one does.



The cover is very soft and "flappy" (hope the picture makes you understand what "flappy" means in my mind ), though it's flappy it still flops back into shape afterwards again, without deformation.


The cover is especially thick on the sides (the sides with the speakers), It also adds some thickness to the screen, so when the keyboard is out there will be slightly less space above the top row of keys.


This cable is awesome, though its made for Amazon's Kindle, its still just an micro USB cable, so I ended up buying two of them, one for having in my jacket and one for the office.
Much more handy then the standard cable that you have to roll up.
Beware though, I bought another cable from Proporta before this, which turned out did NOT have data capabilities, only charging. They changed the description on the item after I pointed it out to them, so it only says charging capabilites now.
So just have this in mind if you decide to go for another cable then this one.



The covers texture is very nice and soft to the touch.
Also, theres a screen protector in the package as well, which is definitely not bad, it has a plastic texture (good) which I prefer over the rubber texture (bad), which are more grippy/sticky and requires more pressure.

And some links
N900 Silicon Case from QuBits: http://www.amazon.co.uk/gp/product/B00327QUCK/
Retractable micro USB cable:http://www.amazon.co.uk/gp/product/B0031XZM6U/

Hope this can help protect all those innocent N900s out there

Looks terrible man.

That being said, I find the silicon cases offer good protection at the sacrifice of looks (my 5800 case did anyway). The hard cases, OTOH, can be quite fragile at the tabs.

How well does the sliding function work?

Do you have a link to the actual item?

You don't notice that the two case parts are attached in any way, they slide freely. You'll only notice that you're N900 has put on a little weight

About the links, just look in the bottom of the first post

I have a similar silicon case (glossy black finish).

True, it is a gimp outfit for my n900 but the protection is superb - I've dropped it a couple of times and the rubber absorbs the impact quite well.

I nearly bought a hard case (with thin rubber coating) but thought it would only "transfer" the shock of a drop to the n900 itself.

Anyway it only cost me £2.99 (including delivery!) from Ebay

It does look ugly as hell and it looks like I am talking into someone's dildo but I don't care my n900 is safe!

I bought one of these just after I got my phone a month or so ago. I have to say, contrary to the review above, that I did not feel that it was a suitable case. The main issue I found was that the 'flappy' case had no way of gripping to the phone so it would regularly slip off - especially while using the slider. It just felt like something very cheap and having a case which was hanging off after pulling the phone out of your pocket is not a great design in my book. Luckily, however, the case is very cheap so I didn't feel bad after throwing it in the bin!

I now have no case, but the more expensive leather ones from nokia look more suitable. Any reviews?

I also got this case from Amazon, I thought it was terrible, didn't fit tight to the phone at all and flopped around all over the place. I'd imagine after a few days/weeks of usage it would get even looser and just fall apart.

Was not impressed at all.

Agree with this review. The case is far too loose to be usable. I've been using mine for just over a week and the top and bottom parts of the screen cover are already stretched and loose. I tried holding the case of with double sided tape, but the silicon is too smooth to stick well.

............fail

I agree that if the rubber had been more firm and hardened then it is now, it would be much better.
But considering what else is out there, and taking the devices design into account, its actually two parts that slide apart, I don't see how else it could have been done.

It's the best solution so far I think between protection and functionality, where I would imagine the Nokia CP-408 would feel more like a man purse and with the CP-321, you have to get it out of the cover before you can access the screen.

But yes, harder rubber would definitely make this cover better, and it's sort of a gimp suit for the N900, though I haven't experienced it falling off when sliding the keyboard open, coming of by accident or any deformations.

I have the same item. 3 months later, the case is no longer hold the n900 very firmly like before. it will get a little bit "loose".