Basics of inflation

I quite like the new journal Physics from APS because it has nice overview articles which are particularly good for learning something about topics outside ones expertise. There is a good article Can we test inflationary expansion of the early universe?
It explains the basic ideas behind inflation [including the broken symmetry associated with the inflaton field], why it is necessary in standard big bang cosmology, to solve the "horizon" and "flatness" problems, and the hope of actually finding more than circumstantial evidence for inflation.