beside the already mentioned features,this could be also important:
1) batteries - mostly Li-ion accu pack, but for example, Pentax K-x uses 4 AA batteries or a rechargeable ones (for example, I use NiMH Sanyo Eneloop batteries), newer Pentax K-r uses Li-ion pack, but is able to use also 4 AA batteries.
2) the viewfinder size and coverage - for example the Olympus 4/3 cameras - at least the Exxx series have very small viewfinder in my opinion.
3) chip - today most DSLRs have CMOS, but some have the EXMOR CMOS chips which have lower noise and thus can use bigger ISO.
4) focus system - could have influence on focus speed - depends on user needs (and also on used lens)
and some (? almost minor) features:
built-in HDR mode, AF assist light for low light conditions, remote shutter - IR or wire connector?