15:00 Nov 24, 2010 

I think Dariusz has a good point - that some prescriptivist grammarians have advocated treating two subjects as a noun phrase rather than two separate nouns in this case.

But from a descriptivist point of view/if you follow the advice of applying the proximity rule, a Google search shows:
"there was a dog and a cat" = 996,000 hits
"there were a dog and a cat" = 8,720 hits

13:25 Nov 24, 2010 

It depends on which position you're willing to adopt...

13:22 Nov 24, 2010 

there was a dog and there was a cat, therefore was.............there were two dogs and a cat would be the only way were would be commonly used and understood

13:07 Nov 24, 2010 

According to the Grammar Book (Celce Murcia and Larsen Freeman, Heinle & Heinle, 2nd Edition), the prescriptive rule says, "With there subjects, the verb is singular or plural depending on whether the NOUN PHRASE following the verb is singular or plural. Hence, "There ARE a book and a pen on the table." However, research shows that many people apply the proximity rule in this situation (subject verb agreement should occur with the noun nearest to the verb). Hence, "There IS a book and a and pen on the table." Thus, the actual usage preference of native speakers differs from the traditional prescription. The context in which language is being used and the discourse community of the participants will determine what is acceptable usage.

09:22 Nov 24, 2010 

I'm asking myself whether there is any difference between this and a sentence such as "There is bread and cheese on the table" - you would never think of saying "There are bread and cheese on the table", even though turning it round you would say "Bread and cheese are on the table".