If you happen to be writing something set in Victorian London (and that might include a steampunk story) this resource might be useful: The Victorian Dictionary – Exploring Victorian London. There are plenty of other great resources such as Booth’s Poverty Map. The only weakness with the dictionary is that I am not sure it is still being maintained.
As I bonus here is a link to some free fronts on Fontspace you might want to use for a book cover or any other piece of Victoriana you might need: Free victorian fonts.
What other resources are worth listing? Let me know!