The good thing about using personalized online services from a single provider is that you only need to sign-in once to access all the services, and there aren't many (if any) companies which can match Google at the number of services provided.
# Webmail ( Online Email )
I don't think many will object to my choice of Gmail in this space. Google started it out as an invite-only email service with a previously unimaginable, humongous storage of 1GB. Later, the quota was increased to 2GB and it keeps on rising as we speak. Many competitors followed suit with GB-sized inboxes, but there are certain features that kept users glued to Gmail :
- (Nearly) 100% spam protection - Web users used to be afraid of posting their email ids on any forums or giving to websites for subscribing to services, due to fear of spam. The amount of spam has tripled in the last two years, but Gmail inboxes remain clean. From the days of using 'honeypot' email addresses for possible spam, Gmail has taken users to the state where they can post their primary email address anywhere, and still feel confident that spam will never reach the Gmail inbox ( I did see one get past Gmail's spam protection yesterday, but that was in more than three months! )
- Conversation View - Google's novel idea of grouping related messages together was a boon to frequent email users. Before it, we would quote the original message thread in every message, increasing the size of mails being shuttled back and forth, thus increasing latency. Now, we can just type-in our response and send the email on its way without having to worry about losing track - as long as the subject line remains the same (even if 'fwd:', 'fw:' or 'Re:' are prefixed), Gmail will organize our mails for us.
# RSS (Feed) Reader
Google Reader is what I use, being a simple and easy-to-use service. It wasn't the first service I used, but it is the only one I've used more than once. Even though it is a beta product (as with most of Google's services), it has been quite stable. The recent addition of Google Gears brought offline functionality to GReader.
# Word Processor / Spreadsheet App.
Simply because I don't have to sign-in to one more service, I use Google Docs & Spreadsheets. Features include collaboration with simultaneous edits, ability to publish documents, inbuilt chat with people currently editing the document, tagging etc. Competitors in the field include the Zoho Suite of products, which was recently in the news for bringing offline functionality to the browser using Google's own 'Gears' technology to its range of products, before Google could implement it in its own Online Office suite. Zoho does have a much wider variety of offerings, all of which are listed at www.zoho.com
If you have better suggestions, lets hear it in the comments.