Load balancing two ADSL routers - any recommendations?

[Chris G]

I have two phone lines and two ADSL routers running with different
ISPs. These provide internet access for a small network of (mostly)
Ubuntu linux machines.

I am setting up a small 'server' machine which, among other things, I
would like to handle the internet access by providing load sharing
and failover.  I've found various bits and pieces of information about
doing it myself (scripts using 'nexthop' and 'weight' in ip commands,
etc.) but I was wondering if there are any ready made applications
which would make things easier for me.

I have found 'balance' but it seems more oriented towards balancing
load on multiple servers in my LAN rather than balancing load between
two routers linking to the internet.

Does anyone have any suggestions for ready made load balancing
software for Ubuntu?

-- 
Chris Green