It’s virtually impossible to determine a source IP over TOR due to the use of multiple proxies. But TOR will only work in situations where you can configure an application w/ a proxy. So it may not protect ALL activities. While traveling between proxies, the data is securely encrypted. But ultimately your data has to exit the TOR network somewhere, in the clear, before being passed to the final destination. So it doesn’t protect your anonymity if you expose sensitive information within that data. You’d still have to use SSL (https) or similar measures to protect the data from eavesdropping at the exit point. And it can be VERY slow (all those proxies take their toll).
HotSpotVPN (there are others, I just picked this one as an example) protects ALL your traffic because it uses a MS VPN, one that takes over the environment, completely. However, it's only anonymous in the sense you have ONE level of indirection between you and your destination. Ultimately discovery is possible by the VPN provider or anyone demanding that information from them. And like TOR, your data is “in the clear” once it reaches the VPN provider. So again, only using something like SSL (https) is going to prevent eavesdropping (if you’re particularly paranoid). And most of these public VPN services are not free. On the plus side, it's MUCH faster than TOR.
You can find these w/ a simple Google search. Like the VPN, you have ONE level of indirection between you and your destination. And most are free. But these proxies often come and go. And many you’re not even supposed to be using (some naive user has left them open, or worse it’s a honey pot, someone looking to eavesdrop and grab sensitive information). And speeds vary greatly. And of course you need to configure a proxy for any application that needs to use it. And it’s subject to eavesdropping, yada yada. So in general, I don’t find public proxies all that practical or safe. But I included them because it is one more possibility and *might* be appropriate in some instances.
You also have to remember that w/ any of these technologies, you're behind someone else's firewall, at least one (w/ a VPN or public proxy) or more (w/ TOR). So technically you can't really use any of them for ALL activities, not if that includes the need to support unsolicited inbound requests (remote desktop, online gaming, etc.).