What does the bible say about homosexuality? I was recently listening to a podcast and the preacher said that he has looked through the entire bible and could not find anywhere where it says that homosexuality was a sin.

Where does the bible stand on this? What verses talk about it?
There's an entire Wikipedia post regarding this subject.  (Thus it's my source as it's easily referenced.)
1
Leviticus 20:13 is the first:

13 “‘If a man has sexual relations with a man as one does with a
woman, both of them have done what is detestable. They are to be put
to death; their blood will be on their own heads.

2
Genesis 18-19 has the story of Sodom and Gomorrah, where homosexuality was a big part of their culture.  The town was destroyed for their wickedness.

Genesis 19:4-5
4 Before they had gone to bed, all the men from every part of the city
of Sodom—both young and old—surrounded the house. 5 They called to
Lot, “Where are the men who came to you tonight? Bring them out to us
so that we can have sex with them.”

Ezekiel even talks about this event here:

Ezekiel 16:49-50
Now this was the sin of your sister Sodom: She and her daughters were arrogant, overfed and unconcerned; they did not help the poor and needy. They were haughty and did detestable things before me. Therefore I did away with them as you have seen.

These verses clearly state that Sodom was destroyed because of they were haughty and did detestable things.  While Ezekiel isn't clear which detestable things were done, the Genesis account only indicates rampant homosexuality (possibly alluding to public, homosexual orgies) as the cause for this phrase &quot;detestable things&quot;.
This also echos the Leviticus scripture showing that God finds homosexuality detestable.
Looking at the account of Sodom and Gomorrah, we have to either conclude it was homosexuality that was detestable, or something that was not written about.  But why would Moses have included homosexuality in Genesis if it weren't the &quot;detestable thing&quot; for which God was destroying the city? In fact, if it wasn't one of the primary reasons for God destroying the cities, why write about it at all? It simply becomes another attribute of the city.
It's hard (if not impossible) to separate the destruction of Sodom from the concept of homosexuality.
3
In the New Testament, there is Romans 1:26-27

26 Because of this, God gave them over to shameful lusts. Even their
women exchanged natural sexual relations for unnatural ones. 27 In the
same way the men also abandoned natural relations with women and were
inflamed with lust for one another. Men committed shameful acts with
other men, and received in themselves the due penalty for their error.

Then there's 1 Corinthians 6:9-11 and 1 Timothy 1:8–10, which refer to sexual sin on a more general basis.  Those previous three are pretty solid references, though.