Every month I try to put together a collection of really handy resources. I may not have discovered them this month, but I have certainly used all three and would encourage readers to investigate all of them.

I intentionally do not include many links here - it’s not a scatter-bomb approach, definitely quality over quantity.

ThickBox is one of those tools you take for granted. It just works. And it works well. I know countless projects I have worked on could use this little work horse - the only downside is the (obvious) dependency on javascript.
Check out ThickBox

Vector Magic (out of Stanford Uni) might not be a service you use very often, but whenever you find yourself in need of some vectorised images it should be your first point of call. The team that put this together seem to have spent a lot of time making it work pretty much perfectly. I was very skeptical when I first tried it, but have since become a convert.
Go visit Vector Magic

Another useful little javascript tool is this validation pack. Live Validation turns boring and hideously user-unfriendly web forms and turns them into an (almost) enjoyable experience for the end user. I use it, and recommend it.