Question: I have two Internet connections, how can I have downloads go through one and uploads go through the other without a new router?

I was thinking two network cards in a computer, but how do you connect to both and route downloads/uploads to the different connections?

Answer: 
[Dispatch proxy](https://github.com/Morhaus/dispatch-proxy) may work here, and in fact this is one of the use cases suggested, and may do even more. 

1. You need two connections, and ideally if they're on seperate routers *non overlapping* ip address ranges.
2. run dispatch proxy (or I guess any proxy), and bind it to one interface. Tell software to use that proxy
3. Dispatch-proxy would also let you do 'naive' load balancing with 2 interfaces and one dispatch proxy instance. It'll either let you combine multiple internet connections and/or set the proportion of connections (not traffic) that go through each.
I am always amazed by people here who put weird answers, anyway

Yes you can make that, but it's tricky here by using QOS
So lets say you have 2 routers each one have different WAN IP and both of them gives your PC same StaticIP for both Ethernet/Wireless card 
easy for now :P 
the next step is using QOS service
On the first router
0 upload
X download
the second one
X upload
0 download

now if you want to browse something your internet explorer will not open any site

The tricky thing is to change the MAC address of your wireless/Ethernet card and make both of them have the same MAC "now people will vote down for this part, because everyone know the MAC not important for web browsing Well some websites like Facebook use MAC address and WAN IP in the same time"

**BUT** you still can't open any site simply because when you enter a domain/site on your browser your browser will send a command to DNS server then the DNS server will connect you to a server to bring the website for you, when you block the download on your first router the server can't send you the site ok you have a mac address but your WAN IP on the second router is different so the server can't know that's you

To solve this problem you need a network MASK to make both WAN-IP work as one address, so you need a DNS server for that :)