The following describes the keyboard I'm currently using, and probably represents the majority of the keyboards that come with new PC computers. I don't know of Macintosh and other computer keyboards, or older layouts of PC keyboards. And don't even get me started with Dvorak or other odd things.
The keyboard has 105 keys - older models have only 102 (no Windows keys).
Left side
First row: Esc, F1-F4, F5-F8, F9-F12
Second row, unmodified:
§ 1 2 3 4 5 6 7 8 9 0 + '
With shift:
½ ! " # ¤ % & / ( ) = ? `
With AltGr, keys 2-4 produce @ £ $ and 7-0+ produce { [ ] } \
Third row:
Tab q w e r t y u i o p å "
(the quote mark is actually umlaut key - with shift, it produces circumflex (^) and with altgr it produces tilde (~). AltGr+E produces Euro sign (€ = fallen-over Quake II logo).
Fourth row:
CapsLock a s d f g h j k l ö ä ' (last is * when shifted)
(Enter key spans the end of both third to fourth row.)
Fifth row:
Shift < z x c v b n m , . - Shift
First key shifted >, | with altgr. last three keys ; : _ shifted.
Sixth row:
Ctrl LeftWin Alt Space AltGr RightWin Menu Ctrl
Right side
This is fairly same what can be found from other PC keyboards: On the first row PrintScreen/SysRQ, ScrollLock, Pause/Break; then below it Insert, Home, PgUp; Delete, End, PgDn, and below it cursor keys.
Number pad has numlock, /, *, -, numbers and decimal comma, and big + and Enter.
Strange things to note
The most useless keys on this keyboard is probably the key on the top left corner under Esc - it produces section sign (§) and one-half vulgar fraction (½). Personally, I have never needed this, and the fraction thing sort of smells of typewriters. The section sign is sort of plausible because some people actually need it, but...
And how about the shift+4 deal then, "¤"? General currency symbol???
Euro symbol could have been placed under AltGr+1 or AltGr+5 (better there), because that's where the rest of the currency symbols are, anyway.
XFree86 cleverly uses RightWin as MultiKey, which is pretty cool.