Hi,
I just thought I'd share a discovery I expect some may be interested in.
If you've experimented with moving keys around on keyboards you may have found that the keys with bumps on them (F and J on qwerty) fit into the keyboard differently from the other keys (upside down, or at a 90 degree angle, relative to the other keys - and sometimes the keys in different rows are a different shape). I've had three cheap keyboards with that issue. I decided to buy a HP K2000 (a cheap, standard, wired USB keyboard) a couple of days ago because it omits the right hand side windows key, which I never use, in favour of moving right-ctrl (and home/end, pgup/pgdown, del/insert, and the arrow keys) closer to the others (it uses the old arrangement that I'm used to from when I was young (I'm 35)). When I popped the J key out to stick it in its new position I discovered that it had the same alignment as all the other keys (I'm on the first step of tarmak at the moment). And keys on different rows are exactly the same shape. And HP include a type of rubber cover with the keyboard, which is relatively comfortable to leave in place, which has its own bumps in F/J (qwerty) position on them, so if you leave it there after swapping keys around you still have bumps in the familiar F/J positions (as well as in F and J's new positions... but while learning via tarmak the original bumps are quite helpful).
This makes is very convenient to switch layouts on this HP K2000 keyboard at least (perhaps other Hewlett Packard keyboards are similar), but since they don't seem to advertise this 'key symmetry' feature I thought I'd give a shout out (I'd like a typematrix or such ergonomic keyboard, but won't be shelling out more than $30 for a keyboard in the foreseeable future :-)
No pics because this forum doesn't seem to support them, & if I host them off-site they may disappear in months, while this thread may be relevant for years... my god...
..oh yea, I don't know if anyone will use this, but I'm editing /usr/share/X11/xkb/symbols/us (US being the default keyboard layout set during install) in Debian for a quick dirty way of setting the various layouts while progressing through tarmak. Just edit as root and restart.