Seems like Linux filesystems have improved even without LVM.
It's entirely possible to resize / filesystem online, at least for ext4 (I expect ext3 too.) This isn't too much of a surprise but a second trick mentioned in the link below, and the fdisk man page, can be used to resize a root filesystem without a recovery disk. Basically, used fdisk to delete the root partition entry and recreate it starting at the same block but extending past the old ending position.
No hanging at the graphical login now
Edit: just to be clear; fdisk can be used to resize the partition, then, resize2fs can be used to resize (increase only for online) the filesystem.
partitioning - How can I resize an ext root partition at runtime? - Ask Ubuntu