ipinfodb.com provides a free service wich let you obtain geolocation info about any ip address. you can access this info parsing the content returned by this page.

the request must be done in this way

http://ipinfodb.com/ip_query.php?timezone=true&ip=204.236.220.71

UPDATE

The above url is not longer valid because to a New APIs are being introduced with API key. you must register in this site to get access to the info.

now you must use a url like this

http://api.ipinfodb.com/v2/ip_query.php?key=&ip=74.125.45.100&timezone=true

and the response look like this

<Response>
<Ip>204.236.220.71</Ip>
<Status>OK</Status>
<CountryCode>US</CountryCode>
<CountryName>United States</CountryName>
<RegionCode>53</RegionCode>
<RegionName>Washington</RegionName>
<City>Seattle</City>
<ZipPostalCode>98144</ZipPostalCode>
<Latitude>47.5839</Latitude>
<Longitude>-122.299</Longitude>
<TimezoneName>America/Los_Angeles</TimezoneName>
<Gmtoffset>-28800</Gmtoffset>
<Isdst>0</Isdst>
</Response>

Now using a TIdHTTP component you can get the result of the request to this page.

uses
  Classes,
  ComObj,
  Variants,
  IdHTTP,

type
 TGeoInfo   = record
  Status        : string;
  CountryCode   : string;
  CountryName   : string;
  RegionCode    : string;
  City          : string;
  ZipPostalCode : string;
  Latitude      : string;
  Longitude     : string;
  TimezoneName  : string;
  Gmtoffset     : string;
  Isdst         : string;
 end;

const
 UrlGeoLookupInfo  ='http://ipinfodb.com/ip_query.php?timezone=true&ip=%s';
 UrlGeoLookupInfo2 ='http://backup.ipinfodb.com/ip_query.php?timezone=true&ip=%s'; //backup server

procedure GetGeoInfo(const IpAddress : string;var GeoInfo :TGeoInfo);
var
  lHTTP  : TIdHTTP;
  lStream: TStringStream;
  XMLDoc : OleVariant;
  ANode  : OleVariant;
begin
  lHTTP   := TIdHTTP.Create(nil);
  lStream := TStringStream.Create;
  try
      try
        lHTTP.Get(Format(UrlGeoLookupInfo,[IpAddress]), lStream); //get the request
      except
        lHTTP.Get(Format(UrlGeoLookupInfo2,[IpAddress]), lStream); //if something is wrong try using the backup server.
      end;
      lStream.Seek(0,0);
      XMLDoc := CreateOleObject('Msxml2.DOMDocument.6.0');
      XMLDoc.async := false;
      XMLDoc.LoadXML(lStream.ReadString(lStream.Size));
      XMLDoc.setProperty('SelectionLanguage','XPath');//use XPath to parse the xml result
      ANode:=XMLDoc.selectSingleNode('/Response/Status');
      if not VarIsNull(ANode) then GeoInfo.Status:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/CountryCode');
      if not VarIsNull(ANode) then GeoInfo.CountryCode:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/CountryName');
      if not VarIsNull(ANode) then GeoInfo.CountryName:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/RegionCode');
      if not VarIsNull(ANode) then GeoInfo.RegionCode:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/City');
      if not VarIsNull(ANode) then GeoInfo.City:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/ZipPostalCode');
      if not VarIsNull(ANode) then GeoInfo.ZipPostalCode:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/Latitude');
      if not VarIsNull(ANode) then GeoInfo.Latitude:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/Longitude');
      if not VarIsNull(ANode) then GeoInfo.Longitude:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/TimezoneName');
      if not VarIsNull(ANode) then GeoInfo.TimezoneName:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/Gmtoffset');
      if not VarIsNull(ANode) then GeoInfo.Gmtoffset:=ANode.Text;
      ANode:=XMLDoc.selectSingleNode('/Response/Isdst');
      if not VarIsNull(ANode) then GeoInfo.Isdst:=ANode.Text;
  finally
    lHTTP.Free;
    lStream.Free;
  end;
end;