GadgetGuy
(Formerly Shermie)
A tomato knife is an invaluable tool. To me, it is one of those things that most folk can live without but when you use one, you will never go back to using other knives. A bit like a foil cutter.
This is the one in our house. Outrageously expensive! Years ago I had a cheaper, slightly smaller and better version. Similar to @morning glory's one above.
p.s. I am obsessive about keeping all kitchen knives sharp. So much so when I go away on holiday I take at least one knife with me!
I hope that you don't fly anywhere. They'll think that you're a terrorist if they find it in in your carry-on bag(s)!!!!