Let's have a look at them.
SKPWI.DAT: This file can be used for skipping the Software inventory Process for a partition or for a folder. If you want to prevent software inventory on a drive/partition or folder you can create a hidden file named SKPWI.DAT and place it on the root of the drive/partition/folder.
NO_SMS_ON_DRIVE.SMS: This file is used to prevent ConfigMgr from installing binaries to a volume. By default, when you install ConfigMgr on a remote Site System, the SMS Site Component Manager Service installs the binaries (files and folders) for the Site System on the NTFS-formatted volume that contains the most free space. You may want to use an NTFS volume other than the default volume for your remote Site Systems by preventing ConfigMgr from enumerating certain NTFS volumes.
ARCHIVE_REPORTS.SMS: This is a client side file and is used when Hw/Sw inventory troubleshooting needs to be done. When troubleshooting ConfigMgr client software or hardware inventory, you might want to retain the XML files that contain details on what the latest scan discovered (regardless whether the scan was a full scan or just a delta).
More information on this can be found on MS TechNet.