HamLog CloudLog is a cloud based amateur radio logging service. Its functionality is very similar to the popular logging application for the iPhone/ipad and Android.
The mobile app
HamLog has the ability to synchronize (pull/push) to the cloud to ensure you're always carrying the most up-to-date log at all times.
Imagine bringing your iPad out into the field and logging a few contacts. Then, once you have Internet access (3G or WLAN), pushing those contacts out to a web-based central repository.
Then you grab your phone and pull those logs, or the whole thing, down from that repository.
Your log is always up to date.
HamLog CloudLog operates on a subscription model. It is free (ad supported) to upload, download and add logs from the web interface and the mobile app.
If you choose you want more than just synching, the subscription option cost is only $9.99 per year.