To reply to an above post, it would not be difficult to have a system where TOW, Rwy and Temp from automated METAR retrieval could then calculate V-speeds and put them on the loadsheet as one last, final gross error check.
Yes I know that MEL items, flap settings, anti-ice etc will alter take-off settings, but it would be better than this situation at the moment.
The technology should be there, it shouldn't be relied on, but would be a little like the third AI.