Using WKT data in GIS systems

[MrMark]

I've recently started looking into using spatial ETL on Mysql (not the best-endowed database in this respect, but never mind). Now to find a distance between 2 points I can use trig calculations for given latitude and longitude co-ordinates. I can find these co-ords for each post code I give easily enough in Multimap, for example.
Now the GIS pages I've perused seen to indicate that using WKT (well known text format) allows you to calculate distances using built-in gis formulas (even in Mysql). However I can't find anywhere (spent several hours on google) that converts long/lat easily to WKT, or gives the WKT data for relevant zipcode/postcode. Does anyone know if such a site or tool exists?

[MrMark]

Well it turns out I didn't really need the WKT data. I can calculate distances between two points (more accurately) using latitute and longitude figures.
Incidentally, for those interested, there seems to be a lot of opensource geo data available here [Edit:mainly US data thobut]:
maxmind page
Also, there's a lot of geo-related stuff in the mysql magazine found here (Issue 4)
mysql magazine
Happy reading - for those into Mysql!

[basshead]

We use MySQL GIS functions for some shape data and point/radius calculations. You have to be careful with the more advanced functions as they only implement complex shapes as 'minimum bounding rectangles', i.e. the shape they use in the calculation is the smallest rectangle that will contain the shape in question, which might be banana shaped. To get round this we narrow down results first then do a further refinement in code using Geotools (Java API) which uses the proper shape.