Silent Update shows and controls content (post/page) modification date. Basically you can choose whether you want to update modification date or not when save post/article. It's a plugin that you should have just in case. If you are still not convinced there are few cases I’m sure you will need Silent Update:
Usage of this plugin is extremely simple. Once you edit some of your post in administration area you should see something like that:
On the right panel you can see box called "Modification date". It’s box created by Silent Update. It consist of following informations:
By default checkbox is disabled - it means that posts will update their date. If you save article, you will notice that modification date changed. If you click checkbox and save article, modification date won’t change - that’s it!
You can find this WordPress plugin in official WordPress plugins directory: Silent Update. It's completly free so I would be thankful for any PayPal donation (use button located at the bottom of current page).
If you are still hesitating whether install Silent Update or not, e-mail me. Don't forget to check out my other plugins like Gonzales or Online Readers - I think you may be interested in them. Meanwhile...