How to add extra value to form?

are you taking about the off-yellow box that the browser shows you when you mouse over something? or are you talking about a homemade tooltip solution?

if it's the first, it is the 'title' attribute, so you would want to do :title => 'look at me!' in the html options for the tag. however, i believe IE will show you the alt attribute, so if you do both :alt and :title, you should be safe.

well then you are going to have to rely on using the element events to show/hide your tooltips

something like:

<%= text_field ..., :onfocus => "show_tooltip(...)", :onblur => "hide_tooltip(...)" %>

i don't know how you are implementing your tooltips so i can't really provide more than that.