Necessary preface: I think it's highly unlikely that we'll get an Electoral College tie, and I don't really think it's a big deal if we do -- assuming that Republicans in the House would have the votes (which appears highly likely), they would simply announce immediately that they were voting for Mitt Romney, and everyone would agree that the election was over with Romney the winner. Recount and lawsuit issues could leave the election muddled, but a tie per se is highly unlikely to do so.
At any rate: someone over the last few days was tweeting out an old blog post which argued that the problem could be fixed by simply increasing the size of the House of Representatives by one, to 436. That would make the Electoral College number odd: 436 plus 100 from the Senate plus three for the District of Columbia under the 23rd amendment would equal 539.
It's a bad idea! Sure, it would solve the Electoral College problem, if you think it is a problem (I'm skeptical, but there is at least some possibility of mischief if the election goes to the House). But only at the expense of having an even number in the House, which just pushes the problem there. The Senate by design has an even number, but also a tiebreaker; the House really would have a mess if the parties had an absolute tie.
But really this is just an excuse to mention that the obvious solution is DC statehood. Then you get to keep the House at 435, but with the repeal of the 23rd you eliminate the extra three. Post-statehood, you have 435 plus 102 plus 0, for 537.
(The way you get around the Constitution is that Democrats draw a New Columbia map that includes all of the regular residents of the District except for a handful of reliably Democratic voters, and move that as a regular statehood resolution while simultaneously moving a Constitutional amendment... you could either do the amendment to simply repeal the 23rd amendment electoral votes for the resident-free remaining Federal District, or you could make DC a regular state and get rid of the Federal District entirely. Given that the choice for Republicans would be to agree to the amendment or give the Democrats three extra Electoral Votes, my guess is it would take about a week for the thing to get through Congress and enough states. Once, that is, Democrats had enough votes to pass the statehood law through both Chambers. Of course, this only happens in years with unified Democratic control).
Okay, look -- I know that the House is often not at full strength, and survives just fine with an even number of Members. And, yes, once again, I think that an Electoral College tie is both unlikely and, if it happens, unlikely to cause trouble. But as long as people are talking about it, I might as well bring this one up again.