I have now sideloaded over 450 files to my iPad Kindle app. For those who aren't up on the lingo, sideloading means copying files into the Kindle app directly from your PC. You might want to do this if you have a bunch of non-DRM mobi files on your PC and want to get them to your iPad Kindle app.
Previously, this required you to Jailbreak your iPad, or if you had a Mac, you could use a program called iPhone Explorer. Although iPhone Explorer was available for Windows, it didn't work with the iPad Kindle app. Now, version 2.1 of iPhone Explorer (
http://www.macroplant.com/iphoneexplorer/) works with Windows.
1) Download the 2.1 or later app from the link above onto your windows pc.
2) Install it on your pc.
3) Connect your iPad to your PC with USB.
4) Run iPhone Explorer and navigate to Apps then com.Amazon.Lassen then documents then ebooks
5) Using your regular windows folder tools (windows explorer) find the .mobi books on your computer and drag them to the ebooks folder on iPhone Explorer
6) If the iPad Kindle app is open, you may have to close it and reopen it for the books to show up.
Issues that you may run into:
1) Sometimes, iPhone Explorer seems to lose track of the folders/files on the iPad. Just close the program and reopen it.
2) It appears that the app is limited in how many books it can handle. Once I loaded a bit over 450 books, the app stopped working.