I am aware of the "troubleshooting" thread, but I hope if it's ok if I keep just one post here for my personal findings and experiences. I will try to keep it updated. First, again, thanks to the h-e-n team for providing us with this .

Trying the usb-sticks of different kinds seems to work fine, however it is a little bit quirky, least to say. Its difficult to find the actual 'key' to when it works and not. Sometimes unplug-plug works, sometimes I do both that and shutting off the h-e-n gui, sometimes switching off-on the vbus power, sometimes re-enumerating. I'm not sure but sometimes the 'lsusb' command seems to work also.
I'm not sure, maybe you already seen these problems that it suddenly stops working and you have to just try some of these things. I just wanted to let you know. Best thing probably would be to check my kernel logs every time I stumble in to problems, haven't had time yet though.

I have a SATA/IDE to USB adapter kit, and I will try to connect an internal ide dvd drive to it and see if that works and then play some dvd in it. That would be nice, just the looks of that setup. If that works I'll finally join youtube and upload a video on that...just to kick some iCrap and droid butt.

The setup of my dreams (but the most difficult one) would be my usb dvb dongle. It would be the ultimate thing to brag about to friends and the guys at work (if that thing would ever fly). I guess there is little hope that it doesn't require external powering from a hub, but it doesn't hurt to try. The problem is, first I got to see if there are any drivers out there and in such case I guess they need to be rebuild for the n900.
I'm wondering though what the right player would be....is vlc capable to access the stream from such video input driver?

Well, tests will continue, I've got a 1TB truecrypted usb drive to test, an additional external usb drive with three partitions on it. One "20in1" usb memory card reader will also be a nice test. The wireless Rumblepad2 would be a nice thing to get working (connecting the receiver I mean)...but I guess it requires some drivers as well.

EDIT:
Working:
* All my tested usb flash sticks and harddrives so far ntfs, fat 32 and truecrypt works just fine.
* Tested 1TiB Packard Bell Carbon, mounted trucrypted ntfs on it, worked flawlessly. Copied some large files (around 500 MB). It did suddenly drop power once and drive shut down completely though and I had to remount (as sdb1 instead), might be related to cable but not sure.
* 3.5" IBM Usb Floppy disk drive in hub. Manual mounting needed. Played around with old floppy disks!
* Managed to enumerate dvb-t stick perfectly running in hub, will fill in all manufacturers, brands and respective id's here later.
* 4-port hub (will fill in that name/brand/id too).
* Enumerated usb mouse. worked nicely with hid scripts (will fill in id's later).

FAIL:
* 7-port hub "Konig". Will check some logs next time. Will check id's from my ubuntu.
* Intermittent failure to enumerate anything. Logs must be checked by myself for some useful info.

Observations:
* Two times the screen backlight was darkened while unplugging hardware. Flipping the screen lock/unlock switch got screen back. Must be power related somehow? Any other reports on this?