You can't set up intersting tags like "sql-server~", to get quick searches for wildcarded interesting tags.
The system allows you to enter it and displays it correctly initially. Selecting it gives the desired results, but when you return to the main page either via the browsers back button or by selecting the site logo the "~" has been stripped off.
I've just discovered that I don't need to add "mp3~" (for example) as an interesting tag - if you've got a wildcard in your interesting tags clicking on it does the substitution for you so you get the search you want.
I'll leave this question here for now as it does seem to have raised another issue.