Some more - safe for work in this case - suggestions and this time its numbers based suggestions.
1) Buying and selling items gives speech experience.
Actively training it would remain significantly more efficient and I was thinking something along the lines of roughly 0.1% per item purchased or sold ... more bonus experience then an effective way to actively train it.
2) Buying and selling prices are affected by speech.
Speech 0 to 49: Items are more expensive to buy and sell for less.
Speech 50: Buy & sell values are as they are now.
Speech 51 to 99: Buying stuff is cheaper, Selling stuff gives more money.
Pretty much a simple 45 degree slope where everything starts out more expensive but given enough speech training items become significantly cheaper and sell for most of what was paid for them (or more then what was paid for them in come cases if making a few credits profit is important) - something like starting at 50% more expensive and selling for 50% less at 0 speech increasing over time to things being 50% cheaper and selling for 50% more at 100 speech, using the current buy and sell rates as the average ...
As an example of use:
Generic Pants
Normal
Buy Value 10, Sell Value 6
Speech 0
Buy Value 15, Sell Value 3
Speech 100
Buy Value 5, Sell Value 9
There are plenty of ways to make money in game that are faster (along with having other positive effects more often then not) so something extra for players that want to grind speech up.
3) Max stats dialog choices
Some alternate solutions to problems for character that have one or more attributes at maximum - intimidating someone who thinks they are strong by showing how strong the player character is, so for example:
Scaring the boss character in the slums into being more reasonable with a display of overwhelming strength ...
[Smash the table (99 strength)]
(The don and henchmen are paralyzed by your show of force and seem more willing to listen to what you have to say)