For the 1st S-H War, you can use the following [all in 15mm]:
Danes in shako: ERM Colonial Brits in Shako and Eureka Danish infantry in shako [not advertised on site but ask]
Danes in kepi: QRF Danes 1850, Minifigs ACW Inf. Frock/kepi among others of the same style [frock coat/kepi], Eureka Danish infantry in cap [not advertised but ask]
Danish artillery: QRF Danish artillery 1850, other artillery crews in kepi/frock
Danish dragoons: QRF Danish dragoons 1850
S/H infantry: QRF S/H infantry, Eureka S/H infantry, 19th Century Minis Crimean War Russian infantry in summer dress [no command but can be added from QRF]
S/H dragoons: QRF S/H dragoons or other manufacturers FPW dragoons [Essex, Outpost Wargame Services, Minifigs, etc.]
S/H artillery: QRF S/H artillery
Prussians, Bavarians infantry: FPW infantry can be used if the boots are painted over for pant/shoe combination. The best thing would be to buy Outpost Wargame Services, as their figures are highly adaptable – shave the shoulder rolls, prime, paint over boots, though any FPW infantry would work if the boots are covered and made into pants
Minor German states: depends on the uniform, if not in any of the uniforms above, try using Minifigs ACW Marines in Frock and Shako for Brunswickers, Crimean War Brits for Saxons or 1859 Austrians for Saxons [still confused on their uniform]
German States cavalry: either Prussian or Bavarian, use FPW. Same goes for the minor states cavalry if they followed Prussian or Bavarian dress. Nap. Brit. dragoons in shako work for Brunswickers
German States artillery: same as above, the problem is the Brunswick artillery in frock/shako – try 1859 Austrian artillery, the shako is rather small but might work.
Swedish/Norwegians: Infantry – Eureka S/H in helmet are perfect. Cavalry – use FPW Bavarians. Artillery – use FPW Bavarians, just paint over the boots to add pants.
I'll be posting a more formal list to the 'Schleswig Wars' Yahoo! group on Monday or Tuesday.
Hope this helps. If you need more info on what is possible in 15mm for the 1st S/H War email me at: jestarnes66@gmail.com and I'd be happy to help. I've also developed a list in 15mm for the 1848 Hungarian War, if anyone is interested.