Gliffy allows you to work on diagrams and charts on-line and without installing any software. So kind of like Visio without all the features, but the benefit of getting it from any and sharing it / collaborating on it easily.
Twiddla is a tool to help meetings and conference calls – which I know you all love. How many times have you all learnt over the phone and said “and could we move the box to there” and of course no one knows what you mean. So you spend more time describing what you mean than discussing it. Well stop doing that and instead draw and annotate your images, documents and website – all together, at once.
Dafont is simple. Free fonts which you can install on your computer to give some extra zing to your docs and presentations. Check with your PC guys first that you can install fonts before you get carried away though!