Array formula in cell B2:

=INDEX(List, MATCH(MIN(IF(ISBLANK(List)+COUNTIF(B1:$B$1, List), "", IF(ISNUMBER(List), COUNTIF(List, "<"&List), COUNTIF(List, "<"&List)+SUM(IF(ISNUMBER(List), 1, 0))+1))), IF(ISBLANK(List)+COUNTIF(B1:$B$1, List), "", IF(ISNUMBER(List), COUNTIF(List, "<"&List), COUNTIF(List, "<"&List)+SUM(IF(ISNUMBER(List), 1, 0))+1)), 0)) + CTRL + SHIFT + ENTER.

Copy cell B2 and paste it down as far as needed.

Named range

List ($A$2:$A$15)
What is named ranges?

Download excel sample file for this tutorial.

Unique and Sort-numbers-and-text-cells-using-excel-array-formula.xls
(Excel 97-2003 Workbook *.xls)

Functions in this article:

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given condition

IF(logical_test;[value_if:true];[value_if_false])
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE

INDEX(array,row_num,[column_num])
Returns a value or reference of the cell at the intersection of a particular row and column, in a given range

MIN(number1,[number2])
Returns the smallest number in a set of values. Ignores logical values and text

ROW(reference) returns the rownumber of a reference

MATCH(lookup_value;lookup_array; [match_type])
Returns the relative position of an item in an array that matches a specified value

ISNUMBER(value)
Checks whether a value is a number and returns TRUE or FALSE