I didn't want to raise old threads about this topic because the ones I spotted dealt more with the nature of virtual game tables [VGT] or market implications.  Rather, I'd like to talk about executing a game via VGT, a new exercise for me.

Virtual gaming is not my first choice for delivering a great game, but for a few reasons I'm facing the possibility of using it.  Perhaps the community here can help me avoid some pitfalls or offer sage advice.

Here is a snapshot of what I'd like to execute:

- system will be OD&D or D&D 3.x
- software will be the suite of RPTools with chat support using Skype

I'm planning on running the game in two different 'modes' in order to better accommodate player schedules:  Live VT time will be used for combat-heavy or site-based adventures.  Player-driven or story-laden components will be played via some asynchronous medium (e-mail, wiki, pbp).  I tentatively plan to host two VT sessions a month with play-by-post between.

I'm operating off of a few assumptions here.  Feel free to dash them as you see fit.  I could use a lot of pointers.

A) I shouldn't burden the game with a lot of house rules or custom gimmicks as we begin; the new medium will take enough getting used to as it is.

B) By scheduling VT sessions I am at increased risk of railroading my players.

We've discussed the potential problems of "scheduling" site-based adventures in this way.  They've preemptively forgiven me, but it still feels a bit odd to me.

C) You need to have crystal clear rules when playing by post (concerning such things as level of participation required, how much you can "do" per post, not narrating other characters' reactions, etc.)

I don't have much experience with pbp either, so suggestions would be helpful.

This isn't my preferred medium, but it's the next best thing to being at the table with your buddies.  I have been gaming with my primary group this way for a while now.  We use Skype for the voice function (we have no need for video calls), and we use MapTool for the chat, macros, dice roller, initiative, maps, and tokens.  MapTool is a powerful game system neutral program which allows for great flexibility.  We use a private forum for the PbP role-playing in between Skype sessions.  This combination is powerful tool to aid role-playing.  

Off the top of my head, here's a couple things to consider:

Preparation:
You need to have your maps and tokens prepared before the session.  Build your maps and tokens ahead of time.  I try to build maps for several encounters ahead of the current one, just in case.  Also, prepare all your tokens for an encounter, and this means preparing their macros for dice rolling.  I have created a 'blank' or 'starter' macro set which I can import into any token and then customize.  

Skype Courtesy:
It's pretty rare where we have moments where everyone is talking over each other.  It happens sometimes, but our group has reaching a natural rhythm of speaking where someone waits for the speaker to finish before speaking.  It really hasn't been an issue with our group.  As I said, there may be a few rare moments where several people are excited and start speaking at the same time but then quickly realize it and then everyone goes back to speaking in turn.

MapTool Set Up:
Our group has encounter very few technical issues while using MapTool and Skype.  Rarely, Skype will have an issue sometimes.  This is usually fixed by dropping the call and starting it up again, or logging out and back into Skype.  We have a system where the person hosting the MapTool session doesn't host the Skype call as well so it's not such a strain their system.  Also, initially, there may be some minor issues in getting everyone connected for the first time due to firewalls and stuff.  Once you have it hammered out, then it should be smooth sailing for everyone to connect to a host session of MapTool.  Make sure that everyone has the same version of MapTool installed and everyone has the current version of Java downloaded.  If an issue arises where connectivity is an issue, then we usually check to make sure everyone is current with Java and MapTool build.  This usually fixes it right away.

Forums:
We use a private forum for in between Skype sessions for various things like posting maps and images, out-of-character talk and planning, and in-character role-playing.  As a GM, we usually write-up a pre-Skype session post to prepare the players for the coming encounter.  After the Skype session encounter, we then usually post a post-session write-up of the wrap of the Skype session.  

Challenges:
This medium demands preparation due to tokens and maps, so on-the-fly gaming is challenging, but not wiped out immediately.  Once you become familiar with MapTool's functionality, it will be easy for you to throw together a rough map for those times when the players want to go off into the wild blue yonder.  Also, having the global set up with generic dice rolls (i.e. the seven dice standard dice) will make easy to make dice rolls for token you just throw out on the map at a moment's notice.
Sandbox gaming can be challenging if you're not prepared.  Although, if you have plenty of maps already prepared with token macros, then you're golden for this type of gaming.

Thank you kindly for the helpful suggestions.

I am running a Wiki Amber game. I have done a few of these before.
Wikis are great because they are simple to use. I use MoinMoin becuase it has a really intuitive security model so players can run their own threads between each other or with the GM that are invisible to the other players. This works really well in an intrigue rich game like Amber and I think that sort of game where PCs are encouraged to head off and do their own things works well for an Asynchronous game.

The problem is when you want to pull people together for events such as the monthly live sessions you want to run. Now Amber has an advantage again as there are different timelines to explain things but its still an issue. A PC goes down a path does some great stuff, starts of on an encounter then gets a bit sidetracked by real life and when you are due to run the next live session there is a jump for them this can be really hard to fix if you want to stick to your live sessions.

If you do the opposite and keep the party together for the middle bit then this is eay as where ever they are is where you start, but then you get another issue which is that a single slow player can stagnant the thread. If you are all mates this might be fine but I have found in the past that some players get frustrated and drop out becuase the pace is too slow.