Here are two types:

RV-3029-C2 : Extremely Accurate RTC Module with embedded Xtal.

* Offers temperature compensated time (very high time-accuracy of ± 6ppm from -40°C to +85°C and ± 8ppm from -40°C to +125°C.)

* Integrated Temperature Sensor with digital-output and offers 8 Bytes
RAM and 2 Bytes EEPROM for customer's application.


Here is another one:
RTC-4553
• Built-in crystal unit.
• Builtin 30 x 4-bit S-RAM.
• Reference pulse output. (1024 Hz, 1/10 Hz)
etc.