Occasionally, I've glanced at the TryParse method in IntelliSense, but never gave it a test run. TryParse is actually pretty cool. It will try to parse a string and see if it can convert it to a specified data type. This is perfect for query strings as you don't have to mess with testing for null values before either parsing or converting the query string to a data type and also eliminates any runtime errors that may be thrown and/or having to catch them.

string booleanQueryString = Request.QueryString["SomeBoolean"];
string doubleQueryString = Request.QueryString["SomeDouble"];
string integerQueryString = Request.QueryString["SomeInteger"];

double doubleValue;
int integerValue;
bool booleanValue, booleanParseValue, doubleParseValue, integerParseValue;

booleanParseValue = bool.TryParse(booleanQueryString, booleanValue);
doubleParseValue = double.TryParse(doubleQueryString, doubleValue);
integerParseValue = int.TryParse(integerQueryString, integerValue);

if (booleanParseValue)
{
   // Do something
}

if (doubleParseValue)
{
   // Do something
}

if (integerParseValue)
{
   // Do something
}