I'm very happy with the custom forms in 1.8 but as I see no forum for 1.8 suggestions, I will place them here:

1) Add multiple Custom Forms to a ticket

2) Order the forums (both Built-in and Custom)

3) Add a custom textbox to the top (and anywhere else you want) of the topic

4) Split topic into multiple topics

5) Apply different sizes to section breaks in Custom Forms

6) Use HTML in Forum Fields Help Texts

7) Create a list of tickets where a Custom Field matches a certain value

8) Show expiration date of ticket

9) Choose colors based on HEX-codes in Templates