The subject and verb in a sentence must both be either singular or plural. You cannot have a singular subject with a plural verb or a plural subject with a singular verb. The subject and verb have to agree in number.
To make a verb agree with its subject, you must be able to find the subject and verb in a sentence. The basic sentence structure in English is subject + verb, so it is easy to find both elements.
But sentences beginning with there is or there are follow a different order: the subject comes after the verb is or are. Let's look at an example:
Can you find the subject in this sentence? It's bus. Both bus and is are singular, so they agree. (A more colloquial way to write this sentence is to use the contraction for is: There's the bus!)
Here's another example:
Books is the subject of this sentence, and it's plural, so we need the verb are to make sure we have subject-verb agreement.
You can also apply this rule to there was and there were, as well as here is, here are, here was and here were.
Yes, exceptions often occur when there is a list of nouns as subject. Logically, a list of items would be plural and would therefore suggest a plural verb:
But it sounds odd to have are next to a punch bowl, doesn't it? The verb is would sound better:
So which of these sentences is correct? The answer is both. The first one follows the standard rule. But the second is also accepted, and many writers would prefer it because it sounds more natural. Therefore, when the subject after there is or there are is a list of items, you can make your verb agree with the first noun in the list.
Although there is or there are constructions are useful in some situations, some writers prefer to reword the sentence. If you put the list before the verb, you must make the verb agree with the plural list (and not just the closest item):
As long as the subject and verb agree, the style you choose is up to you.
For more information on subject-verb agreement, read Basic subject-verb agreement.