FAHLMAN  According to the developer's website Monocle 1.5.1 was released 01/28/2007 which conflicts with the date noted here.  
(Version 1.5.1)

PEDROTAQUELIM  This little utility is very usefull but today, looking at the activity monitor, I notice that is always 'eating' 41,30 MG of memory... hmmm, that is a little to much... ;-)  
(Version 1.1b1)

PEDROTAQUELIM  Nice! Very nice!  
(Version 1.1b1)

BLOCKSOFT  Really handy piece of software. Only loses one point as it can sometimes be a little tricky to add new search sites.  
(Version 1.1b1)

COPILOTO  This is an incredible piece of software -- it is extremely useful! It doesn't get in the way and you can add all the search engines you want. The killer feature for me is the ability to use it completely from the keyboard, including changing search engines. Gets a solid A+.  
(Version 1.1b1)

SIBELIUS  A little gem - very quick and easy to use, with enough options to make it look pretty good too. Searches from the menubar seem much faster, simply because there's no need to find an open Safari window first.

You can add as many search engines as you want - but you do need to follow the instructions exactly (which I didn't, at first). They're case sensitive.  
(Version 1.0.1)

MACMEND.COM  This is an interesting take on the old huevo thing. However when you compare it to acid search for Safari and the ease of adding or taking out search engines in acid search it starts to fall down. There are so many search engines these days and people like myself based in countries other than the USA want engines linked to their countries and want them with ease. This does not offer that.  
(Version 1.0.1)

HENRIKTEKNIK  Great.  
(Version 1.0)

MACLOVER1.1  I've wanted this for a long time :-)  
(Version 1.0)