Since you've not mentioned having any family in the USA, the only way you could get an immigrant visa would be in the 'employment based' category:
http://london.usembassy.gov/immigrant-visas/employment-based-visas.html
Generally, with exception of people with exceptional abilities that can't be found in US citizens (such as famous actors, footballers playing at international level, research workers at PhD level, top international financiers, etc) it's impossible to get such a visa.
Further, you can't get a visa unless you've
already got an offer of work in the USA. President Obama has pledged to make it harder for US companies to recruit from overseas unless they can absolutely prove that no US citizen could fill the job.
In the unlikely chance that you met all of the necessary criteria, you'd probably still face a very long wait. I had friends who were eligible for immigrant visas because their son, who was married to a US citizen, was already living there. It took them 2½ years to complete all of the formalities.
It's similarly difficult to get into Canada. Click the 'Start' button here:
http://www.cic.gc.ca/english/index-int.asp
The USA has an unemployment rate broadly similar to that of the UK but it's got poorer social care facilities, much shorter holidays, worse employment protection and (in many jobs) lower pay. The federal economy can only be described as 'faltering' at best, with many state administrations currently on the edge of bankruptcy. It certainly wouldn't my first choice (or my one hundredth choice) of countries to emigrate to.
Canada also has a similar level of unemployment. Economically it might be better placed than the USA but, because it relies heavily upon trade with the US, it's still unlikely to flourish in the near future.
Perhaps it's time to learn a Scandinavian language? Sweden, Denmark and Finland have the most competitive economies in the EU, with much higher standards of social provision than many other countries. They often feature in lists of the best places in the world to live and work. You can move there and (if you can find a job) work there with no formalities whatsoever.