Chronology

Ketz Meguleh has a wonderful series of posts on how chronology fits in with our current calendar system, and how it affects us today.

It's worth reading through them all:
Daniel 9
On The 163 Year Discrepancy
When was Adam HaRishon Born?
Rambam on the Year Count
Commentary on Rambam
Rambam - Why Don't We Count Yovel?
Yovel Count of Rebbi Yehudah (also see the first comment)
Galut Bavel in Tanach
Recent Yovels
If more posts are added in this series, I'll BL"N add links to them.