Recently I ordered a second DSL line, and have run into a few hiccups here.
Where I live is pretty remote and the only service provided is 1.5Mb speeds. I ordered another line and have a DrayTek router for both connections. However the problem is, they only load-balance.
I'm looking for a router that is capable of doing Bonding of the two DSL lines. I recently heard about this server that can bond the lines for you for a small fee of $25 a month by sending you two routers that have their firmware adjusted to work with their setup. I have heard many great things about them and one guy who is extremely happy with them. (link: http://us.sharedband.com/)
If possible I would rather not pay an additional $25 a month for something I am fairly sure you could do within your house via hardware.