Well Nokia in their license forbids redistribution of their content, for example the fiasco images they provide to flash the N900. Nevertheless some people ignores that and adapted the sizes of the partitioning inside the images and share them. You may decide on your own, if you honor the license and trust those images to be trustworthy.


Download Gparted-Live-CD.iso file or any Linux-Live-CD image containing gparted application
Burn Gparted-Live-CD to CD or DVD
Install Backupmenu to your N900
Reboot the N900 with keyboard ejected
In Bootmenu type 'w' to export the partitions in read/write-mode
Boot your PC from the Live-CD
If necessary start gparted
Choose the device (hard disk) in the upper right drop down menu should be some 30GB size.
Right click the first partition (approx27GB) and choose 'Resize or Move', use the right handle to shrink the partition.
Click 'Resize'-button (Dont worry you will be asked to apply actions later)
Right click on the second partition (approx.2GB) and choose 'Resize or Move', use the left handle to fill the free space created by the first resizing.
Do not touch the third, aka swap-partition.
Now click apply in the upper toolbar and accept the changes to be applied.
If everything is resized successfully, shut down the PC
On the N900 press 'q' to quit backupmenu and restart Maemo.

Hope that helps!