is it possible to turn your laptop into a usb-storage device? or at least allow a certain folder to be "shared" over usb easily?

This would make it really easy to share files with other laptops or peripherals (pda/mp3 with usb host)

Anyone know of a project? Not easy to find anything (try typing usb-storage linux in google)

If you mean you want to use a laptop as a USB device for another computer, it's not possible. USB is not a machine-to-machine protocol, it's host/client based. Two USB host devices cannot talk to each other. There are some adapters that allow you to do this, but they're basically two network cards built into one device with a crossover cable.

Just buy a crossover cable and use NFS to share files/resources.

I use a crossover cable and a FTP server on the main machine.

No offense, but using a laptop as a USB storage device would be ridiculously expensive. Most laptops are at least $1200 to $1500, and have approx 80G of capacity as an upper limit, while an 80G external USB drive is under $100. Personally I think you'd be better off just buying a USB drive. If you need to transfer files between 2 PC's (perhaps the laptop and a desktop) you might consider just setting up a small home network. Just my 2 cents -- J.W.

I see that the zaurus has this feature on the newest models, and they do run as usb host.

I do own a laptop, i also own a removable hard-drive and a 30gig mp3 player. I do not seek to replace them. This usb-hack would just make it easier to hook up two laptops and share files.

I Have wifi, those removable media mentioned and ethernet cable, but end up using gmail to do transfers just because I'm too lazy to set up a samba/ftp/nfs server and client. Plus it would bee cool to connect the laptop to a different computer and have a portion or a partition pop up as a usbdisk.

most distros should have a sample config file that you can use that works pretty well with minor adjustment.