My first chapter! Sallies are cool, have cool fluff and an even cooler style.
They prefer flamers/melta weapons over other more standard heavy weapons (although they use everything). They are also master artisans, so they make use of master crafted equipment and some of the more valuable vehicles in a marines armory (dreads and terminator suits).
Of course a lot of this is just fluff, but it does help you to start a themed army.
The new codex space marines is rumored to have Chapter Master Tu'Shan of the Salamander chapter as one of the new special characters.
Very fluffy, very fun to play fluffy and cool to look at.