Don't know if any of these have been mentioned, but I've found a couple of apps for the Omnia I'm quite fond of, so thought I'd mention them.
MobiPocket: What I think is an
incredibly comfortable and easy-to-use eBook reader and eBook shop. Can use *.txt, *.pdb and *.html files along with MobiPocket's defaults - I have a few *.pdb Pratchetts
OmniaTHREAD: Excellent app for activating and deactivating the threading of texts (I, personally, prefer it off.)
NoData: Another excellent little app which allows you to toggle the phone's permission to use GPRS/EDGE/HSDPA. You can allow it to ONLY allow MMS connections while deactivating all other internet connectivity until you want to use it.
Palringo: IM clients (especially on a cell) are pretty dependant on preference, but after using a few, including Fring, I must say that Palringo is by far the "neatest" and most unobtrusive to use. There's also an option to have your status message be your location, courtesy of the Omnia's GPS. Although, if you use that, be sure to turn off either the GPS option when you don't want to use it, or the force backlight on option in your GPS settings for obvious reasons.
ScummVM: I'm using the Windows CE ARM package download. ScummVM is basically (in case you don't know) an emulator for DOS games. It works quite well on the Omnia, although it takes a bit of getting used to. There's also a
thread on MoDaCo with a bit more information, specifically regarding playing games on landscape. From experience, Day of the Tentacle, Monkey Island 1, Maniac Mansion, Loom and Gobliiins 1 work pretty well - all adventure games.
Lemmings: I don't know how many people remember this game, but, well, it's BRILLIANT and highly addictive on the Omnia. Apparently there are still some copyright laws regarding this game, so you'll have to find the MAIN.DAT file to play it yourself. It's really easy to find though, remembering that
Google's your friend. If you find it, just put it in the same location as you installed Lemmings and yeah, simple as pie
A couple more potentially useful apps can be found on
MoDaCo.
And, hopefully, I can say that I've contributed something useful to this thread
