By ’simple’, I mean, you don’t have to go through registration and login process to use the web apps – you can directly go there and get the job done. Also, design wise, simple here means a sleek and easy-to-use interface. How does the word ‘useful’ applies? Well, it’s up to you to decide.

TinyPaste

TinyPaste works as a place to share a snippet of text, source code or a bunch of URLs with other people. Paste the text, and you’ll get a short URL to share with other people. With no other options as seen in Pastebin, such as syntax highlighting, this simple app is suitable for a simple and quick solution.

Visit TinyPaste | Firefox extension | Alternative : textsnip

Writer

Online text editor. We never gonna know when we need one. This simple app let you type, save, send and download as .txt or .pdf file. If you don’t really like the dark background, you can change it in the Preference section. You can also create an account if you want to keep all files. Visit Writer

the Awesome Highlighter

Awesome Highlighter lets you go to a website to highlight certain area of text – the you’ll get a URL that linked to the highlighted page. This is going to be useful to show your buddies certain points on an article or a website full of text with no permalinks. However you are limited to only 2000 characters per page. That should be enough right?

Visit the Awesome Highlighter | Firefox Add-On and bookmarklet

TinySong

Search a song, and you’ll get a URL pointing to the song’s streaming audio page powered by Grooveshark. I love the sleek interface design and the AJAX effect. Read more about 5 clean and simple mp3 search engines. Visit TinySong

Popuri.us

A useful web app to quickly check the popularity of a website : Alexa Rank, Google PR, technorati and others. You can also show off your stats by embedding a widget on your site. Visit Popuri.us

Twitabit

If twitter is down, there’s always other method to update your twitter status. One of them is Twitabit. Login there, and you can tweet as usual. Visit Twitabit

Ping-o-matic

Simple. Ping-O-Matic is a service to update different search engines that your blog has updated. Update your blog, ping the Ping-o-matic. Visit Ping-o-matic

…others

and there you go. There’s a lot more out there. Share your favorite apps with us.