To that end I went through the exercise myself and compiled a list of the Limits methods and what the respective limits are, using the helpful resources below.
- "Understanding Execution Governors and Limits", Force.com Apex Code Developer's Guide
- Salesforce Limits Quick Reference Guide
This was a great learning experience for me, as I discovered many old limits have been deprecated, especially the ones previously affecting describe methods! It was also interesting to note that there is no limit on callouts per 24-hour period, or at least none that I could find.