根据IP查询所在地、运营商等信息的一些API如下（根据我有限的一点经验）：
1. 淘宝的API（推荐）：http://ip.taobao.com/service/getIpInfo.php?ip=110.84.0.129
2. 国外freegeoip.net（推荐）：http://freegeoip.net/json/110.84.0.129 这个还提供了经纬度信息（但不一定准）
3. 新浪的API：http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=json&ip=110.84.0.129
4. 腾讯的网页查询：http://ip.qq.com/cgi-bin/searchip?searchip1=110.84.0.129
5. ip.cn的网页：http://www.ip.cn/index.php?ip=110.84.0.129
6. ip-api.com： http://ip-api.com/json/110.84.0.129 （看起来挺不错的，貌似直接返回中文城市信息，文档在 ip-api.com/docs/api:json）
7. http://www.locatorhq.com/ip-to-location-api/documentation.php （这个要注册才能使用，还没用过呢）

（第2个freegeoip.net的网站和IP数据的生成，代码在：https://github.com/fiorix/freegeoip）

为什么其中第4、5两个是网页查询也推荐了呢？是因为两方面原因，一是它们提供的信息比较准，二是使用了页面信息自动抓取（可能会用到我曾经写过的PhantomJS）也容易将其写到程序中成为API。

根据IP查询地理位置信息，我将其写成了一个较为通用的Python库（提供了前面提到的1、2、4、5等4种查询方式的API），可以根据IP查询到地域信息和ISP信息，具体代码见：
https://github.com/smilejay/python/blob/master/py2013/iplocation.py
注意其中对ip.cn网页的解析用到了webdriver和PhantomJS.

代码如下:

#!/usr/bin/python
# -*- coding: utf-8 -*-

'''
Created on Oct 20, 2013
@summary: geography info about an IP address
@author: Jay http://smilejay.com/
'''

import json, urllib2
import re
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

class location_freegeoip():
'''
build the mapping of the ip address and its location.
the geo info is from
'''

def __init__(self, ip):
'''
Constructor of location_freegeoip class
'''
self.ip = ip
self.api_format = 'json'
self.api_url = 'http://freegeoip.net/%s/%s' % (self.api_format, self.ip)

def get_geoinfo(self):
""" get the geo info from the remote API.
return a dict about the location.
"""
urlobj = urllib2.urlopen(self.api_url)
data = urlobj.read()
datadict = json.loads(data, encoding='utf-8')
# print datadict
return datadict

def get_country(self):
key = 'country_name'
datadict = self.get_geoinfo()
return datadict[key]

def get_region(self):
key = 'region_name'
datadict = self.get_geoinfo()
return datadict[key]

def get_city(self):
key = 'city'
datadict = self.get_geoinfo()
return datadict[key]

class location_taobao():
'''
build the mapping of the ip address and its location
the geo info is from Taobao
e.g. http://ip.taobao.com/service/getIpInfo.php?ip=112.111.184.63
The getIpInfo API from Taobao returns a JSON object.
'''
def __init__(self, ip):
self.ip = ip
self.api_url = 'http://ip.taobao.com/service/getIpInfo.php?ip=%s' % self.ip

def get_geoinfo(self):
""" get the geo info from the remote API.
return a dict about the location.
"""
urlobj = urllib2.urlopen(self.api_url)
data = urlobj.read()
datadict = json.loads(data, encoding='utf-8')
# print datadict
return datadict['data']

def get_country(self):
key = u'country'
datadict = self.get_geoinfo()
return datadict[key]

def get_region(self):
key = 'region'
datadict = self.get_geoinfo()
return datadict[key]

def get_city(self):
key = 'city'
datadict = self.get_geoinfo()
return datadict[key]

def get_isp(self):
key = 'isp'
datadict = self.get_geoinfo()
return datadict[key]

class location_qq():
'''
build the mapping of the ip address and its location.
the geo info is from Tencent.
Note: the content of the Tencent's API return page is encoded by 'gb2312'.
e.g. http://ip.qq.com/cgi-bin/searchip?searchip1=112.111.184.
'''
def __init__(self, ip):
'''
Construction of location_ipdotcn class.
'''
self.ip = ip
self.api_url = 'http://ip.qq.com/cgi-bin/searchip?searchip1=%s' % ip

def get_geoinfo(self):
urlobj = urllib2.urlopen(self.api_url)
data = urlobj.read().decode('gb2312').encode('utf8')
pattern = re.compile(r'该IP所在地为：(.+)')
m = re.search(pattern, data)
if m != None:
return m.group(1).split(' ')
else:
return None

def get_region(self):
return self.get_geoinfo()[0]

def get_isp(self):
return self.get_geoinfo()[1]

class location_ipdotcn():
'''
build the mapping of the ip address and its location.
the geo info is from www.ip.cn
need to use PhantomJS to open the URL to render its JS
'''
def __init__(self, ip):
'''
Construction of location_ipdotcn class.
'''
self.ip = ip
self.api_url = 'http://www.ip.cn/%s' % ip

def get_geoinfo(self):
dcap = dict(DesiredCapabilities.PHANTOMJS)
dcap["phantomjs.page.settings.userAgent"] = (
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:25.0) Gecko/20100101 Firefox/29.0 " )
driver = webdriver.PhantomJS(executable_path='/usr/local/bin/phantomjs', desired_capabilities=dcap)
driver.get(self.api_url)
text = driver.find_element_by_xpath('//div[@id="result"]/div/p').text
res = text.split('来自：')[1].split(' ')
driver.quit()
return res

def get_region(self):
return self.get_geoinfo()[0]

def get_isp(self):
return self.get_geoinfo()[1]

if __name__ == '__main__':
ip = '110.84.0.129'
# iploc = location_taobao(ip)
# print iploc.get_geoinfo()
# print iploc.get_country()
# print iploc.get_region()
# print iploc.get_city()
# print iploc.get_isp()
# iploc = location_qq(ip)
iploc = location_ipdotcn(ip)
# iploc.get_geoinfo()
print iploc.get_region()
print iploc.get_isp()