<apex:page controller="DropdownDemoController">
<apex:form >
    <apex:outputLabel value="Select a Name : "/>
    <apex:selectList value="{!selectedAccName}" multiselect="false" size="1">
        <apex:selectOptions value="{!accNames}"/>
    </apex:selectList><br/><br/>
    <apex:outputlink target="_blank" value="apex/Page2?accName={!selectedAccName}">Send</apex:outputlink>
</apex:form>

public DropdownDemoController()
{
    accNames = new List<SelectOption>();
    for(Account acc : [SELECT Name FROM Account LIMIT 5])
    {
        accNames.add(new SelectOption(acc.Name, acc.Name));
    }
}

public void submit()
{
    System.debug('selectedItem is '+selectedAccName);

}