I was curious so I looked - ubuntu has a virtual keyboared installed by default but hidden. You can show the menu items for it by going to System > Preferences > Main Menu and enabling "onBoard" (seems to be under preferences for some reason).
For handwriting recognition you can use "cellwriter". Install it via Add/Remove, or using synaptic (System > Administration > Synaptic Package Manager).
I heard a while ago that "xournal" is a good journal / note taking app, but I've never used it myself (again, install using either add/remove or synaptic).