Karen Fox's thorough survey of advances & standard royalty percentages on the part of romance publishers has been online for quite some time, but I just discovered it today (thanks to Southern Comfort: Diary of a Hype Hag). While young, debuting literary writers regularly take home outsized advances (as the Grumpy Old Bookman phrased it, "Sensible industries boast about how much income is generated by their product; publishers boast about how much they've paid for it."), the romance genre, judging by Fox's information, takes a very cautious approach to untested talent. Some examples from her list:

Dutton/Signet/NAL (single title)

Average advance (first book): $7,500

Average advance (subsequent books): $36,000

Advance range: $7,500 - $85,000

Standard royalty percentage: 8%

Average earn-out: n/a

Genesis

Average advance (first book): $650

Average advance (subsequent books): $2,000

Advance range: $500 - $2,500

Standard royalty percentage: 6% "of invoice"

Average earn-out: n/a

Harlequin Intrigue

Average advance (first book): $4,000

Average advance (subsequent books): $6,000

Advance range: $3,500 - $7,000

Standard royalty percentage: 6%

Average earn-out: $17,000

Range: $11,000 - $18,000