The most likely outcome, as I see it, is a continuation of the present coalition but possibly without Nick Clegg whose own seat looks precarious. The Lib-Dems generally, seem on course to drop to 20 odd seats but that's still a significant number. They have a number of seats where they seem to be safe in spite of their low poll rating.
Milliband might try to form a minority Government with SNP support on a vote by vote basis but it would be electoral suicide to go into a formal coalition with the SNP and either way, such a Government would inevitable be short lived.
In any case, Cameron has first go at forming a coalition so a Tory/Lib Dem/Unionist coalition seems most likely to me.
The way I see it is Labour will definitely join forces with the SNP the SNP is labour only further left, if you look at Hartlepool a Labour stronghold many streets in Manor ward are of Scottish origin, the civic centre is red brick locally known as the kremlin,Ed Milliband is a Marxist oh the irony of it all , labour will have ran out of money within 5 years joined the euro , and the European union will become the new china. We live in a sovereign country with a democracy not perfect but many generations here have not known persecution under communist, or dictatorship rulers be carefull who you vote for
I think Cameron will do a deal with UKIP and Clegg.
According to Cameroon he only needs approximately 20 seats and he takes it, he will definitely not do a deal with UKIP nowhere near enough seats and the red line around coming out of the EU is a stumbling block, he doesn't want to come out of it you see, his only alternative is to stick with the Lib Democrats they will retain enough seats only Clegg will be keen, and he may loose his seat in Hallam, so watch him keep repeating we are focused on winning an outright majority.