Unknown Db file format - best way to find out?
If you are on a *nix system, you can try using the "strings" command on each file to peek at the contents. A header may give you a clue.

e.g.

strings file.dat | head


Here's an example run against a quicky sqlite3 database file.

~$ sqlite3 test.db
SQLite version 3.6.12
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite&gt; create table testtable (id INT);
sqlite&gt; insert into testtable values (1);
sqlite&gt; .quit
~$ strings test.db
SQLite format 3
Ktabletesttabletesttable
CREATE TABLE testtable (id INT)