Most bands tend to find their sound and stick with it, but some are able to grow their style/sound over time while still sounding like themselves. Led Zeppelin did it; their early albums don't sound like their later albums, but they all sound like Zep albums. Metallica did it with their first several albums (KIA through AJFA), but then changed their sound pretty drastically for the black album, and even more with subsequent albums. Opeth followed in Metallica's footsteps, with Orchid through Ghost Reveries being a solid growth progression, but then they changed their sound with Watershed and even more drastically with Heritage. So my question: what other bands have been able to change and grow their style over the course of their careers without "selling out" (Metallica) or completely changing their sound (Opeth, In Flames, etc.)?