There are many Welsh resources available online, including the following:
Web Browsing
Everything is online these days - and you need a Welsh portal to it. Here are some options for Welsh language web browsers:
Google Chrome - How to change the default language of Google Chrome
Emails
To deal with the plethora of emails that invade our inboxes daily, here are some programs that are available in Welsh:
Microsoft Outlook - see the Welsh language packs for Microsoft Office below.
Mozilla Thunderbird - Not yet available in Welsh yet, but worthy of note.