I'd really like to see some imrovements to the in-calculator program editor.

[Anders]

vi should be permanently banned once and for all! One of the few editors that are worse than the one currently implemented in Prime H/W. vi is quite possibly the biggest cumulative destroyer of programmer productivity over the history of programming (due to its time in market, wide spread mandatory usage in comp sci classes, ww presence and horrendous ui).
Notepad++ should be possible to do.