There’s a host of online regexp testers. One that seems to work well is RegexPal.

I noticed that wikibooks has something that seems to be a decent resource on reverse engineering. I have looked through a few chapters and it could use some more contents, but it does seem like a nice page to point interested beginners to.

Red Hat Magazine has a guide to fitting a live Fedora on an USB memory, which can be useful at times.

I have come across a set of notes explaining a plethora of algorithms. The notes were created by Johan Håstad and could come in handy as a toolbox after having identified a problem.

I was completely unaware of many of Haskell’s useful libraries until i stumbled upon a nice reference .

There’s a handy iptables tutorial which covers just about anything one could every want to know about iptables.

It’s always nice to have a tour of the Haskell prelude close when one needs to check up on some function in the prelude.

A nice ruby quick reference.

I usually forget the size limits for different data types in MySQL, so I keep a handy MySQL data type reference close to me.

Personally I some times forget how to merge output streams in bash since I rarely do it (it’s done with >& by the way). Luckily there’s a good bash reference which is handy for those situations.

A handy command list for emacs is always good to have.

I often forget how to create certain math symbols in LaTeX. Luckily I always have a handy chart of LaTeX math symbols close.

Some site use a slightly customised google map. Few use the more advanced functionality such as replacing the map with a custom map and making it more interactive.

There’s a really good site that covers pretty much everything that’s possible to do with google maps. It’s a handy link to keep around as one never quite know when one might need it.