Interesting
I have a habit of checking my MSN chat history occasionally and I find it quite nice to read about it once a while, looking at the past jokes that I've made and things that we've shared and the relationships we once had.
You see, time passes and things change every now and then and that goes the same for relationship. I mean general relationship between friends, family and couples do change...
Take for example, at this certain period of time in life, you have a very close friend and you all would talk about everything under the sun...and after that certain period, things changed and you all started talking less and eventually become obsolete. It's sad but what can we do? Afterall a relationship involves both parties and we just have to put in effort to maintain it...and it's sad when you look back at this conversation history and find that there is no recent updates anymore.
Another example will be between couples. The type of conversation you had before the start of a relationship and in the middle of a relationship is actually drastically different. It would be rather interesting to read it again and figure out what you were actually thinking of then.
So, save your conversation history =)