Well, I made a program to help with different verb forms in Japanese, but it could only run on Windows... so here is a version using HTTP, which means any operating system can use it as long as they have a web browser and an internet connection! =D
Major credit goes to Rita L. Lampkin's book "Japanese Verbs & Essentials Of Grammar Second Edition".

Please realize:
This HTTP version is not complete yet! It is still in the developing stage.
It doesn't deal with desu, like the original program does, yet.
Latest info about this version: Lines are coloured by ending type (can be disabled).

First part - Please type verb (dictionary / infinitive form)
Kana/Kanji: * Kana/Kanji version of Romaji text - I didn't put any example so that it's okay for people who don't have support for Japanese characters installed. ;) - If you leave this blank, the Hiragana of the Romaji will be used.
Romaji: e.g. oyogu
English: e.g. swim
* Optional

If you don't have support for Japanese characters installed, then when you click "Make table", you might get a message saying that you need to install it, even if there was no Kana/Kanji in the text boxes above. To stop this, you can tick the box below.
Disable Japanese characters

If you're interested in what JVS is compatible with, please look here.