Dropbox is a free web-based service that provides up to 2 GB of data storage, and it works with both Macs and PCs. Dropbox will not only help you synchronize your database between computers, it will maintain a safe and secure web-based backup, in case your laptop is ever lost, stolen or damaged.
Many services, like Google Drive are not a safe option for TntMPD, because if two computers both open the TntMPD database at the same time, the last person to close TntMPD would simply overwrite any changes made by the other. One person's changes might simply disappear! Therefore I haven't felt comfortable using a service like this for my data. But Dropbox is safe because it handles conflicts like this differently by creating a "conflicted copy" of the database. This conflicted copy will be detected by TntMPD 3.0 and you'll be prompted to automatically synchronize any changes that didn't get saved in the main file.