The routines and daily lives of todays techno-homo-sapiens are shaped in a way like never before by employing the power of web services. A web service seeks to solve the computing problem of an individual over the web. Gone are the days when you need to code your own program to solve problems. As the solution delivered over web is XML based, it can be transefed by the standard HTTP protocol and all you need is a web browser to acces them. The W3C defines web service as "A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards."
Here's a list of some useful free webservices:
http://www.lionwap.org/validationtest.html
Validates the email address first by checking if its syntactically correct ( better to use client side script to do this) and later checks whether an email server is found at this address. Check out the error message at the bottom which gives a good clue.
http://centralops.net/co/
http://www.ippages.com/
http://network-tools.com/ or http://nwtools.com/
http://visualroute.visualware.com/ (includes visual search)
www.tracert.com/cgi-bin/trace.pl
Solutions for ipaddress to domain name or location( lots more),email validation, root tracing, path tracing (great to see what path the data traverses from source to destination), getting your browser details etc. These are implemented through basic ping,traceroute,nslookup etc commands besides looking up the HTTP Header. On top of that you can get source code of all their services.
http://www.xe.com/ucc/
http://www.x-rates.com/calculator.html
Online Currency conversions, can also compare/plot graph for the history of currencies.
Services By Google
There are a hell lot of services being offered, most of them can be found
here.Some of the less known and used services I have listed here.
TranslateTranslate text between some of the common languages or translate a whole webpage.
Currency ConversionTo use our built-in currency converter, simply enter the conversion you'd like done into the Google search box and hit "Enter" or click the Google Search button
Example:
3.5 USD in GBP
currency of Brazil in Malaysian money
5 British pounds in South Korean money
2.2 USD per gallon in INR per litre
Definitions
To see a definition for a word or phrase, simply type the word "define," then a space, and then the word(s) you want defined. If Google has seen a definition for the word or phrase on the Web, it will retrieve that information and display it at the top of your search results.
Example:
define World Wide Web
define Computer
File Types
Google has expanded the number of non-HTML file types searched to 12 file formats. In addition to PDF documents, Google now searches Microsoft Office, PostScript, Corel WordPerfect, Lotus 1-2-3, and others. The new file types will simply appear in Google search results whenever they are relevant to the user query. If you prefer to see a particular set of results with a specific file type (for example, PDF links), simply type filetype:[extension] (for example, filetype:pdf) within the search box along with your search term(s).
Q&A
Want to know the population of Japan? What currency is used in Algeria? The birthplace of Bono? Hit us with a fact-based question or query (like "population of Japan") by typing it into the Google search box. We'll search the web and display the answer at the top of your search results page. We also link to our source for this information so that you can learn even more.
Site Search
Searches a specified site. To search a site key in "site:sitetosearch.com query" into the search box.
Google code APIs
Google recently released APIs for its products and services which can be found at http://code.google.com.
Watching what is happening when a web service is called. Also provides some useful web-services.
http://www.mindreef.netHere is an elegant list of web-services.
onto any flat surface and could experience a real keyboard typing. Shown here is an example of 
