I was thinking about the swap of territory between France and Italy in Savoy, and how the borders in much of Africa and the Middle East are arbitrary, have countries ever tried to peacefully swap land in order to improve both nations?
Well, Italy's most recent changes to its NW border aren't so much the result of peaceful negotiations.
To begin with, both Savoy and the County of Nice had been annexed by France after the Agreements of Plombières had been signed in 1860; Italy then occupied those regions from 1940/3, but after the war it was made to cede a relatively smallish part of its territory (the villages of Briga Marittima and Tenda, the Roia valley as well as parts of neighbouring comuni) with the 1947 Treaty of Paris.
However - France (or, better, de Gaulle) also claimed the Valle d'Aosta, bits of Piedmont and the town of Ventimiglia as war reparations, but was stopped short by the other western Allies who felt that Italy had been punished enough with the loss of much of its North-Eastern terrirories. Borders have stayed the same since then, the only point of contention being Mt. Blanc's summit - an issue neither government seems to care much about.