This is by no means an exhaustive list, a lot of links are to Wikipedia articles, but it will hopefully serve as a quick reference list for people who want ideas, maybe for a throwaway reference in a single thread or similar.

Names:

Roman names - Forum Romanum; text of The Private Life of the Romans by Harold Whetstone Johnston
Some Roman slave names
Roman names - Carol Ashby; a wordpress site with research by a published author
Roman personal names

Roman Names on Nova Roma

List of Roman consuls A list of all the known historical consuls. From Wikipedia - useful for discovering new/unusual nomina and cognomina from the historical record

List of Roman praetors As above; a list of the known historical Roman praetors, on Wikipedia
Roman name generator - this site has generators for all sorts of things - check under the 'real names' tab for things like Egyptian and Phoenician names as well as the linked Roman name generator. I believe that the site owner has put in actual historical names from various sources, but don't quote me - as always, when coming up with a name for a new character, run it past the staff to ensure it fits with the board!

List of Roman gentes

List of Roman nomina

A list of praenomina can be found on the Wiki page on praenomen

List of Roman cognomina

Sex and Sexuality:

Homosexuality in Ancient Rome (subsection on male/male sex)
Reader's reply to query in fail_fandomanon
Sexuality in Ancient Rome: Master-slave relations

Slavery

Slavery in Ancient Rome
Roman debt bondage (abolished in 326BC in this form)

A Bitter Chain: Reflections on Slavery in Ancient Rome
Interesting discussion about the status of slaves here (homo, non persona est - a man but not a legal individual)

Slaves in Ancient Rome: Numbers, Sources and Laws

Roman Slavery: The unique features and longevity of slavery system in antiquity

Roman slavery and rate of manumission

Ancient Roman Slavery

According to Marcel Mauss, in Roman times the persona gradually became "synonymous with the true nature of the individual" but "the slave was excluded from it. servus non habet personam ('a slave has no persona'). He has no personality. He does not own his body; he has no ancestors, no name, no cognomen, no goods of his own."(Source)

servus … homo est, non persona; homo naturae, persona iuris civilis vocabulum

a slave ... is a man (human being), not a person; man (human being) is a word of nature, person (is a word) of civil law.

It means that a slave is a human being, but not a person, in the sense that a "person", legally speaking, is a human being with civil rights and duties (and, of course, a slave cannot have civil rights). (Source)
 

Places

List of Roman place names in Britain: Settlements
List of Latin names of cities

Maps

Map of Roman Britain - includes overlays for villages, villas, vici, roads...
Map of Roman Britain, c 150AD
Roman Britain: Maps from Roman Britain

Kinda for fun but... Tube-style map of Roman roads in Britain
 

Religion

Roman festivals
Lemuria
Nemoralia