The above mentioned are great! The echo Layla24 will have a choice between 8 analogue ins and outs and ADAT I/O.

THe MOTU 2408 is also worth checking out with it's 8 analogue ins and outs (wait for the 2408 mark 2 to ship- it will have balanced TRS connectors!).

Do you use a digital mixer like a Yamaha O3D or O1V? If so then you could look at something like Creamware Pulsar 11 or Soundscape Mixtreme and get either the ADAT or TDIF card for your mixer and hook that directly to the card. Both of these options offer powerful DSP based mixing seperate from the computer as well as expandability and compatability with most audio software.