Over the past few months, I've been using bitfield - a script to decode the fields within a register. It does neat stuff like this:
[jk@pokey ~]$ bitfield IOC_PTE 0xb80000000140031c decoding as Cell IOMMU Page table entry 0xb80000000140031c  Page protection: 0x2 [write] Coherence required: 0x1 Storage ordering: 0x3 [reads & writes] RPN: 0x1400 IOID: 0x31c
It's handy for those "did I really tell the hardware to do that?" problems.
Download and documentation over here.