What metrics you should watch

If you're not active in the credit markets on a daily basis, here are a few things you can observe to judge their health and trend.

CDX - this is a widely quoted basket of 125 names; bear in mind, it's devoid of banks/brokers.  The wider the spread, the weaker the market.  You can find it on Bloomberg under CDXI or in the WSJ.  This is what you should watch for intraday moves.  

Barclays Credit Index OAS - this is a much broader index.  It is quoted daily but is really only hand price twice a month when the Barclays traders mark each bond.  Watch this for longer term trends.  You can find this in WSJ.

TRACE volume - this is the secondary volume in the credit markets (cash bonds only)

Vix - you know this one; higher Vix oft portends a lousy credit market

2 year swap spreads - this is the rate (actually a spread) at which highly rated banks lend to each other.  As this rate spikes, it shows reticence in the market to extend credit.

If you follow these indicators, you will have a good feeling for the health of the market.