Translated in 1954 by John Ciardi, this edition published in 2001. It's enough to make you forswear the Three Beasts of Worldliness forever (expecially the "She-Wolf of Incontinence", that sounds real inconvenient).
Dante's Inferno was a great glimpse into the people of the 1300's and how Dante viewed them. He racked and stacked them into the 9 rings of Hell, according to their sins. Dante took the realism of real events and people to make this book very interesting.
The last time I read "The Inferno" was back in 1971 as an undergrad in English Lit, but I did recall liking it and I wasn't disappointed the second time around. This editon has a brief biography of Dante, a decent introduction and lots of "endnotes" (ie footnotes) to the text. Longfellow's translation is quite readable, although I can't say how it compares to more modern translations; however the fact that it was still used in 2003 when this version was published must be a testimony to its' durability.