Microsoft.SharePoint.Publishing object has a great little WebService, http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.publishing.spellchecker.aspx

The web service is aptly named the Spelling Service and actually leverages code from the Microsoft.SharePoint.Publishing namespace.

You can find this WebService on your own SharePoint farm at http://mysite/_vti_bin/spellcheck.asmx. In a nutshell, you simply pass the web service ‘chunks’ of text, and it will identify whether or not any of the words are misspelled. Additionally, you can also specify the language (LCID) or a Boolean flag to auto-detect the language based on the word(s) submitted.

Unfortunately, Microsoft is a little vague about this WebService, other than to say it exists and that you can call it…

WebServiceBindingAttribute(ConformsTo = WsiProfiles.BasicProfile1_1)]
[WebServiceAttribute(Namespace = "http://schemas.microsoft.com/sharepoint/publishing/spelling/", 
    Name = "Spelling Service", Description = "This web service identifies spelling mistakes and recommends suggestions for correction.")]
[SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel = true)]
public sealed class SpellChecker : WebService

When the response is returned, the XML will contain various nodes, which include the index of the text ‘chunk’ where spelling errors appear, the words ‘flagged’ and the type of spelling error that occurred (RepeatWord or UnknownWord). An additional node that you will notice is the offset field, which identifies the location in the input where the misspelled word begins. Lastly, a spellingSuggestions node is also returned which includes the misspelled word and a list of suggestions in the sug node.

Sure, there are other spelling web services out there, but if you already own SharePoint (Standard or higher) there’s no reason to look elsewhere.

Here’s a list of other WebServices that come with SharePoint:

 

Friendly Name

Location

Description

Alerts

/_vti_bin/alerts.asmx

Provides methods for working with alerts for list items in a SharePoint site.

Area Web Service

/_vti_bin/areaservice.asmx

Provides an area interface for remote clients.

Authentication Web Service

/_vti_bin/Authentication.asmx

Provides ability for Web services to operate in conjunction with forms authentication.

BDC Fields Resolver Web Service

/_vti_bin/bdcfieldsresolver.asmx

BDC Fields Resolver Web Service for Clients

BDC Web Service

/_vti_bin/businessdatacatalog.asmx

Business Data Catalog Metadata Web Service

CMS Content Area Toolbox Info Web Service

/_vti_bin/contentAreaToolboxService.asmx

This Web service is designed for the SharePoint Designer client to use.

Copy Web Service

/_vti_bin/Copy.asmx

Provides methods for copying items between locations in the SharePoint environment.

List Data Retrieval Web Service

/_vti_bin/DspSts.asmx

Provides a method for performing queries against lists in Windows SharePoint Services.

Document Workspace Web Service

/_vti_bin/DWS.asmx

Provides methods for managing Document Workspace sites and the data they contain.

Excel Services Web Service

/_vti_bin/ExcelService.asmx

Provides methods to call the Excel Services remotely or work as a callback for Web Parts.

Forms Web Service

/_vti_bin/Forms.asmx

Provides methods for returning forms used in the user interface when working with the contents of a list.

Forms Services Proxy Web Service

/_vti_bin/FormsServiceProxy.asmx

Provides methods for Forms Services to proxy requests to remote data sources from Web based forms.

Forms Services Web Service

/_vti_bin/FormsServices.asmx

Provides methods to call Forms Services remotely or to work as a callback for Web based forms.

Imaging Web Service

/_vti_bin/Imaging.asmx

Provides methods that enable you to create and manage picture libraries.

Lists Web Service

/_vti_bin/Lists.asmx

Provides methods for working with lists and list data.

Meetings Web Service

/_vti_bin/Meetings.asmx

Provides methods that enable you to create and manage Meeting Workspace sites.

Official File Web Service

/_vti_bin/officialfile.asmx

Provides methods for sending files to a records repository.

People Web Service

/_vti_bin/People.asmx

Provides methods for working with security groups.

Permissions Web Service

/_vti_bin/Permissions.asmx

Provides methods for working with the permissions for a site or list.

Published Links Web Service

/_vti_bin/publishedlinksservice.asmx

Office clients and other applications can obtain the list of published links on the server that are targeted to the current user.

Publishing Service Web Service

/_vti_bin/PublishingService.asmx

Provides methods to remotely work with the publishing service.

Search Web Service

/_vti_bin/search.asmx

Allows access to Enterprise Search results from client applications and Web applications outside of the context of a SharePoint site.

SharePoint Directory Management Web Service

/_vti_bin/sharepointemailws.asmx

Provides methods for remotely managing distribution groups.

Site Data Web Service

/_vti_bin/SiteData.asmx

Provides methods that return metadata or list data from sites or lists in Windows SharePoint Services.

Sites Web Service

/_vti_bin/sites.asmx

Provides methods for returning information about the site templates for a site collection.

Slide Library Web Service

/_vti_bin/SlideLibrary.asmx

Provides methods for slide library callbacks or remote publishing of slides.

Spell Check Web Service

/_vti_bin/SpellCheck.asmx

Provides methods for spell checking callbacks.

Search Crawl Web Service

/_vti_bin/spscrawl.asmx

Provides methods for remote Microsoft Office SharePoint Server 2007 farms to crawl a local farm.

Search Web Service

/_vti_bin/spsearch.asmx

Provides methods for remotely performing searches within a Windows SharePoint Services deployment.

Users and Groups Web Service

/_vti_bin/UserGroup.asmx

Provides methods for working with users, site groups, and cross-site groups.

User Profile Change Web Service

/_vti_bin/userprofilechangeservice.asmx

Provides methods to query the user profiles change log remotely.

User Profile Web Service

/_vti_bin/userprofileservice.asmx

Provides a user profile interface for remote clients.

Versions Web Service

/_vti_bin/versions.asmx

Provides methods for working with file versions.

Views Web Service

/_vti_bin/Views.asmx

Provides methods for working with views of lists.

Web Part Pages Web Service

/_vti_bin/webpartpages.asmx

Provides the methods to send information to and retrieve information from Web services.

Webs Web Service

/_vti_bin/Webs.asmx

Provides methods for working with sites and subsites.

Workflow Web Service

/_vti_bin/workflow.asmx

Provides methods to work with workflows.