Google offers more ways to use its instant messaging client. Here's a (supposedly complete) list:
Desktop applications
* Google Talk client - available only in Windows. Distinctive features: voice calls, voicemail, file transfers, Gmail notifications. You can also chat with people from other IM networks using Jabber transports.
* Jabber clients. Google Talk uses Jabber, so any Jabber client can be used to connect to Google's servers. Use this option if you have Linux, Mac or you want an all-in-one instant messenger that lets you talk to your friends from Yahoo Messenger, AIM etc. A nice all-in-one cross-platform instant messenger is Gaim.
Mobile applications
* MGTalk - third-party Java application that includes Gmail notifications.
* Talkonaut - another third-party Java application. Distinctive features: call your contacts (not free), easy way to add contacts from other IM networks.
* OctroTalk - Windows Mobile client for smartphones and Pocket PCs. It supports chatting and talking with other Google Talk users.
* Google Talk for BlackBerry. You can "add, delete and rename contacts, know when [your] friends are online and available, leave conversations and resume them later, copy conversation text into memory and even be notified when a message is being typed."
Web applications
* Google Talk is available in Gmail. This is particularly useful if you want to reply to a mail from someone who is online, but the email is not the most appropriate way (you need an immediate answer). Also Gmail is the place where you can search your chats (add label:chats in front of your query).
* Go to google.com/talk and click on "Launch Google Talk". A pop-up window will open and you'll be able to chat with your friends. Unlike the Gmail version, here you have tabs and a richer interface.
* Add a gadget to Google Personalized Homepage or to Netvibes. Use this option if you have your personalized homepage always open in the background.
* Add it to your browser's sidebar.
In Firefox, click on this link: Google Talk Sidebar to create a bookmark that opens in the sidebar. Now all you have to do is to click on the bookmark to load the gadget.
In Opera, create a new panel by clicking on this link: Google Talk Sidebar. To see the new panel, press F4 and select it from the list.
* There are also third-party sites like Meebo that let you chat with your friends from other IM networks as well.