zSpreadsheet

zSpreadsheet is a spreadsheet app for iPhone, iPad, and iPod touch that supports spreadsheets up to 26 columns by 2500 rows.

Complex calculations are possible including use of functions such as sum, product, average, logarithms, trig functions, and raising to a power, using expressions like =SUM(A1:A10).

Cells' contents can be made bold, italic, left or right aligned, centered, colored, and 4 fonts choices are available. Cells' borders can be made into solid lines.

You can print to AirPrint-compatible printers.
You can email a spreadsheet as either HTML or as a CSV attachment.
You can import CSV files from email attachments via Mail.

zSpreadsheet lets you make line graphs and bar graphs of selected rows' data.