More information please! Posts as brief as yours are nearly impossible to answer.

Material - stainless steel, fireclay, silgranit, enamelled cast iron?

Decor of kitchen - contemporary, traditional, something in between?

Budget - you can spend $200 or $1200, or anything in between.

Is this your only sink, or will you also be having a prep sink?

D-shape or rectangular?

Undermount, surface mount or apron front?

Usually I ask whether the person prefers a single bowl or double bowl sink, but your one piece of information says 30" cabinet, and given that size, I think you pretty much have to go single bowl. If you get a double bowl for a 30" base cabinet, neither bowl will be big enough to set down a pan to soak, or give you much room.

Aggie,

I had a 30" base and wanted the biggest single stainless undermount sink I could fit in there. I didn't want it to be too deep, so I limited my search to 8" sinks.

I found these: (hope the links work!) I ended up with the Affluence, which is pretty nifty:

http://www.pexsupply.com/Kraus-KHU-100R3-30-30-Undermount-Single-Bowl-Kitchen-Sink-14090000-p

http://www.google.com/products/catalog?client=safari&rls=en&q=30%22+kitchen+sink&oe=UTF-8&um=1&ie=UTF-8&cid=10801216467799012971&ei=x51ES9yVJ43WM4_-uPEB&sa=X&oi=product_catalog_result&ct=result&resnum=4&ved=0CCAQ8wIwAw#ps-sellers

http://hi.atgimg.com/pdf/1605/23ssns43_webspecsheet.pdf [9"]

http://www.seamlesssink.com/showroom.php