I have some ideal adding into simutrans.
1) Add country flag stand with national flag will be fun:) It can also include simutrans logo flag:) If it can present it with gif in simutrans, it will be great:D
2) Adding military like tanks and demolish building will be nice also:) Also it is not as useful as flag stand, I can it can satisfy for fans of military:D If others like trenches or other military set are added, it will be very very great:D