In late 2008, there was a global financial crisis in which a number of banks, finance companies and insurance companies failed. The causes and effects of this crisis are good research topics because the topics are current and controversial, which means that there is a great deal of information available. International politics connect with this issue because of the role governments played in the management of this crisis, namely in terms of large bailouts.
Economies throughout the world are extremely connected. Tariffs are special taxes that governments impose on imports to discourage these imports and encourage citizens to buy locally. The justifications for and effects of tariffs are therefore a good "lens" to examine international trade.
The IMF is a large fund that lends money to developing nations to improve the economies and lift the standard of living. However, these loans come with certain caveats, such as a commitment to small government policies and reduced public services. A good topic, then is to examine these stipulations in relation to the benefits of the loans, and assess whether the loans are worth it, and if so, for what groups.
Some countries receive food aid from other countries, which is a dumping of free or cheap food into an economy. This food is generally subsidized by more developed countries, and its goal is to feed people. However, as with most large scale programs, there are unintended consequences for these local economies, like a reduction in the price of local food. The validity of food aid and its positive and negative effects are both good places to start for your economics research.