Hardware raid controllers
LSI Logic is one of the main manufacturers for SCSI Raid controllers. Their products are available under their own name and a variety of rebranded cards (Intel, etc).
ICP is the other one main SCSI Raid manafacturer. They have controllers based on gdth, and since they were bought by Adaptec some newer, incompatible controllers. Before that, ICP was, for some time, owned by Intel, so older Intel SCSI Raid cards are also gdth-based.
3ware produces low cost ATA and SATA RAID controllers. The common feeling about their speed and stability is mixed.