I've been busy trying to work out how to base and re base our 'new' and existing 15mm scale Napoleonic miniatures. Unfortunately, or fortunately depending your point of view we have a number of rule sets we are interested in playing. All are, not surprisingly Piquet supplements. The first two 'Les Grognards' and 'Grand Piquet, 2nd Edition' use the same basing system but the third, CdePk (Chef de Piquet) a tactical level game requires a different basing scheme.
So for the infantry I have decided to put two miniatures on a 0.75" x 0.5" base, you can put two bases side by side and you have to right frontage (1.5") for a single base in Les Grognards and Grand Piquet. Put three bases directly behind each other and that's a 3 rank element in CdePK, of course you can do the same with only two bases and have a 2 rank element as well. Which also happens to match the basing for infantry in Napoleon's Battles (1st Edition).
To reduce the hassle of moving around a large number of small 0.75" x 0.5" bases I plan on basing all the miniatures on magnetic strip (the 15mm British are already based in this manner) and then place those bases on metal bases cut to size. For example a 3 rank element for CdePk would be 0.75" x 1.5" and would have 3 of the smaller magnetic bases on it.