From a sobbing four-year old to an expletive-strewn unofficial pro-Obama campaign ad, what have been the stand-out internet memes that have marked the 2012 US presidential race?

Silly, serious, or just plain bizarre. Memes are concepts and ideas that are picked up and spread via the internet or on social media and a number of them have been carried along on the flow of the 2012 US presidential campaign.

Colorado four-year old Abby Evans appeared to speak for the whole of America when she was captured on video by her mother crying because she was "tired of Bronco Bama [Barack Obama] and Mitt Romney".

The toddler's outburst came after she had been listening to constant election coverage on National Public Radio (NPR), especially intense because her home state is one of the critical battlegrounds which may decide the election.

As bloggers and even Time magazine came out in support of Abby's election fatigue, NPR issued an apology to Abby promising: "Only a few more days, only a few more days, only a few more days."

Surely one of the more bizarre viral hits was this speech by Hollywood veteran and long-time Republican party backer, Clint Eastwood.

Looking like something which might be included in a workshop at one of the more experimental theatre schools, Eastwood made his political points to the absent President Obama by addressing an empty chair.

The stunt delighted the assembled delegates at the Republican party convention and promptly hit YouTube where it has racked up hundreds of thousands of views.

Capitalising on the sweary role of Jules Winnfield in Pulp Fiction which arguably made his name, actor Samuel L Jackson effed and jeffed his way around the internet in this unofficial campaign ad in support of the Obama campaign, Wake the F*** Up.

It was made on behalf of the Jewish Council for Research and Education, and parodied a popular book for strung-out parents, Go the F*** to Sleep, which Jackson also read.

A more lighthearted, if not outright silly, hit was this video showing clips of Republican hopeful Mitt Romney at a number of public appearances during the campaign.

His words have been deliberately mis-read and overdubbed by a sound-alike giving rise to lines such as: "Because if Madonna had a wooden statue, she would have gobbled that sardine," and "Centurions from east Asia, near Mumbai, got my cooler and they took my spider jars into prison".

Brownie points on offer to anyone who can work out what Romney actually said.

And sometimes, a throwaway comment can come back to haunt a candidate in an unexpected way. This video was one of a number which were born from a remark made by Mitt Romney about cutting government funding to US public service broadcasting (PBS).

Romney said: "I'm going to stop the subsidy to PBS, I'm going to stop other things. I like PBS, I love Big Bird... But I'm not going to - I'm not going to keep on spending money on things to borrow money from China to pay for."

Cue an outpouring from the official (the comment became part of a campaign ad) and unofficial wings of the Obama camp, ridiculing Romney for using one of the most popular characters from long-running children's education show Sesame Street to illustrate government waste.

With some commentators complaining that the rich array of spoofs and unofficial campaigns risk bringing down the level of debate around the election, for many others (if she was old enough to appreciate them, perhaps even Abby Evans) they have been bright bursts of light relief in a long campaign which is finally about to reach its climax.