Excel2MySQL allows you to import Excel spreadsheets directly as a table into MySQL. To import an OpenOffice Calc file, simply save as xls and then import.
(Full disclosure, I am the author of Excel2MySQL).
It meets all of your requirements:
- Each sheet is imported as a table in MySQL. In fact, the table is automatically created.
- The headers of the table can be used to define the fields of the MySQL Table.
- Excel2MySQL DOES smart analysis on column data type to automatically optimize the table field types (tinyint, smallint, mediumint, int, bigint, float, double, varchar, date, time, datetime)
And more:
- Connects directly to your MySQL Server
- Includes a command line interface, if you need to automate imports.
- Append or replace existing table
- Automatically detect and add new fields in existing table
- Automatically explode Excel merged cells (not the same as unmerge).
- Optionally exclude blank rows and blank columns
- Optionally change spaces to underscores in field names (convenience function)
http://excel2mysql.net

1Wow, the tool looked complicated to install and use, but in the end (thanks to your description) I managed to get it working! One side note: On the Table output step, I had to choose the tab "Database fields", press "Get fields" and then choose "SQL" and then "execute". This was the only way to get the structure automatically translated into a database table. Otherwise the transformation process complained that fields were not found in the table. Maybe you can improve your answer above with this comment? (I have no edit capabilities) – Roalt – 2010-11-15T11:02:58.933
Good Point! I forgot about that (that's what happens when you answer from memory ;). Typically what I do is click on 'Enter field mapping' and use the wizard to map my excel columns to the table (if they have the same name, clicking 'Guess' can save you a lot of time). I'll edit the answer to make sure it reflects your comments. – Edgar – 2010-11-15T16:16:13.423
Considering all the functionality that's in this program, I'll have to find more time to look at the other things you can do with it. It seems very powerful! – Roalt – 2010-11-17T21:09:47.030