I've had a lot of involvement in the commercial world too. The following is a rundown of the packages that are available to which I've contributed something. Most recent packages are at the top of the list, oldest at the bottom.
This is a project put together largely by Craig Scott and Pat Malicki, but Abacus came to me and asked if I'd do the cabview for it. So I did. The package came out late 2002 and you can find details about the Casino Express here.
As a parallel project with the Euro Loco Pack, JustTrains asked for a regional loco and carriage set for the TGV Pack, along with cab and passenger views for Clem Tillier's excellent TGV train set. I contributed the SNCF BB7200 with a full rake of Corail carriages (first and second class), with cab and passenger views. I did the cabview for the TGV with different renderings for each different type of train set. Full details about the TGV Pack can be found at JustTrains website, by clicking here.
JustTrains came to me in mid-2001 on the strength of my free trains and signed me up as the sole developer for their Euro Loco Pack. The result was 100% my own work. It included a varied selection of trains from across Europe all with transparent windows, Superscale detail, custom cabviews and custom carriage interiors. Full details about the Euro Loco Pack can be found elsewhere on my own website, by clicking here.
Abacus asked for contributors to their second "collection" pack and I obliged with a variant of the freeware Plan T / Plan V trainset. I called it the Plan-B (for Benelux) and repainted it in fictional Beneluxrail colours. The RailYard Collection can be found here.
Abacus were the first published to put together an add-on pack for MSTS. They contacted me on the strength of my free trains and asked if they could be included in the Roundhouse. As a result, 75% of that pack was my trains. Included were the very original versions of the Eurostar, Sprinter, NS1200, NS1800, Regiorunner and Koploper. Would you believe I gave them those for free. I know now that they've sold over 20,000 units of the Roundhouse. Let's just call that a 'character building experience' shall we. The TrainSim Roundhouse can be found here.